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1800-102-2727This is the complete JEE Main Maths Formula Sheet and Class 12 Formula Sheet for Limits, Continuity and Differentiability — Chapter 7 from the Aakash Rapid Revision & Formula Bank. This is one of the most formula-rich and concept-dense chapters in the entire JEE Main maths syllabus: definition of limits and existence (LHL = RHL), indeterminate forms (0/0, ∞/∞, 0×∞, ∞–∞, 1^∞, 0⁰, ∞⁰), algebra of limits, L'Hospital's Rule, all 15 standard limits (sinx/x, tanx/x, (aˣ–1)/x, log(1+x)/x, (1+1/x)ˣ=e, xⁿ–aⁿ/x–a formula), important expansions (eˣ, sin x, cos x, tan x, log(1+x), (1+x)ⁿ), Newton-Leibnitz theorem, continuity definition and types of discontinuity, differentiability (LHD = RHD), all 20 basic differentiation formulas, chain rule, product rule, quotient rule, parametric, implicit, logarithmic, and determinant differentiation, trigonometric substitutions for differentiation, derivative of infinite series, higher order derivatives, and Leibnitz formula for nth order derivative of a product. Limits, Continuity and Differentiability contribute 5–8 questions in JEE Main every session. Download the Free PDF below for all formulas in one JEE Main exam-ready reference.
Scroll to explore all Limits, Continuity and Differentiability formulas — JEE Main Maths & Class 12 Formula Sheet
Limits, Continuity and Differentiability is the gateway chapter to all of calculus in JEE Main maths. The concept of a limit is the foundation on which both differential calculus (derivatives) and integral calculus are built. Every derivative formula is defined as a limit of a difference quotient. Every integral is defined as a limit of a Riemann sum. Mastering the limits, continuity, and differentiability formulas in this chapter is therefore prerequisite knowledge for the entire calculus section of JEE Main.
For JEE Main maths, Limits, Continuity and Differentiability contributes 5–8 questions per session — one of the highest counts of any chapter. Questions range from direct standard limit evaluation (sinx/x, (aˣ–1)/x, the 1^∞ form) to continuity and differentiability analysis at specific points, chain rule and implicit differentiation, and Leibnitz theorem applications. The differentiation formulas alone (all 20 basic derivatives) are used in nearly every other calculus chapter including Integration, Differential Equations, and Applications of Derivatives.
Download the Free PDF for Limits, Continuity and Differentiability to access all standard limits, continuity definitions, differentiability conditions, all basic differentiation formulas, and all differentiation techniques in one structured JEE Main maths revision reference.
Definition of Limit (Limits, Continuity and Differentiability — from PDF): A real number l is called the limit of f(x) as x → a, written lim_{x→a} f(x) = l, if for every ε > 0 there exists δ = δ(ε) > 0 such that |f(x) – l| < ε whenever 0 < |x – a| < δ. The function value f(a) is irrelevant to the limit — only the behaviour as x approaches a matters.
Existence of Limit (from PDF — Limits Continuity and Differentiability): lim_{x→a} f(x) exists if and only if LHL = RHL = finite and definite:
LHL = lim_{x→a⁻} f(x) = lim_{h→0} f(a–h)
RHL = lim_{x→a⁺} f(x) = lim_{h→0} f(a+h)
The limit lim_{x→a} f(x) exists iff LHL = RHL (both finite and equal).
Indeterminate forms in Limits, Continuity and Differentiability (from PDF — JEE Main): A form whose value cannot be uniquely determined. The 7 standard indeterminate forms are:
0/0, ∞/∞, 0×∞, ∞–∞, 1^∞, 0⁰, ∞⁰
Explanation of 0/0 from PDF: if k = 0/0, then k×0 = 0 for infinitely many values of k, so k is not fixed. Every one of the 7 forms represents a situation where the limit may exist but cannot be read directly from the expression. Each requires a specific technique to resolve.
Resolving indeterminate forms in Limits, Continuity and Differentiability (JEE Main): 0/0 and ∞/∞ → use L'Hospital's rule OR factorisation OR expansion. 0×∞ and ∞–∞ → rewrite as 0/0 or ∞/∞ using algebra (LCM, rationalisation). 1^∞, 0⁰, ∞⁰ → take logarithm to reduce to 0×∞ then to 0/0 or ∞/∞. Download the Free PDF for Limits, Continuity and Differentiability for all indeterminate form worked examples for JEE Main.
If lim_{x→a} f(x) = L and lim_{x→a} g(x) = M (both exist finitely), then from the PDF — Limits, Continuity and Differentiability:
9 Algebra of Limits rules (from PDF — JEE Main):
(i) lim[f(x) ± g(x)] = lim f(x) ± lim g(x) = L ± M
(ii) lim[f(x)/g(x)] = lim f(x)/lim g(x) = L/M, provided M ≠ 0
(iii) lim[k·f(x)] = k·lim f(x) = kL (k is a constant)
(iv) lim[f(x)]^g(x) = [lim f(x)]^[lim g(x)] = L^M
(v) lim e^f(x) = e^(lim f(x)) = e^L
(vi) lim log f(x) = log(lim f(x)) = log L (provided L > 0)
(vii) lim[f(x)·g(x)] = [lim f(x)]·[lim g(x)] = L·M
(viii) lim (fog)(x) = f(lim g(x)) = f(M), provided f is continuous at M (from PDF)
(ix) Sandwich Theorem (Squeeze Theorem): If f(x) ≤ h(x) ≤ g(x) for all x in a neighbourhood of a, and lim_{x→a} f(x) = lim_{x→a} g(x) = L, then lim_{x→a} h(x) = L. The squeeze theorem is used when the limit of h(x) cannot be found directly but can be bounded between two functions whose limits are known.
L'Hospital's Rule (from PDF — Limits, Continuity and Differentiability): If f(a) = 0 and g(a) = 0 (or both → ∞), then lim_{x→a} f(x)/g(x) = lim_{x→a} f'(x)/g'(x). Differentiate numerator and denominator separately (NOT using quotient rule). Apply repeatedly until the indeterminate form is removed. Works for both 0/0 and ∞/∞ forms. Also applies to x → ∞ cases. Note from PDF: for 0×∞ and ∞–∞ forms, first convert to 0/0 or ∞/∞ before applying L'Hospital's. For 1^∞, 0⁰, ∞⁰: take log, reduce to 0×∞ form, then convert. Download the Free PDF for Limits, Continuity and Differentiability for L'Hospital's rule examples.
The following standard limits are listed directly from the Aakash PDF — every one appears in JEE Main either as a direct question or as a step in multi-part limit evaluation.
Trigonometric standard limits in Limits, Continuity and Differentiability (from PDF):
1. lim_{x→0} (sin x)/x = 1; lim_{x→0} (tan x)/x = 1 [equivalent to lim (sin x/x) = lim (tan x/x) = 1 as x→0]
2. lim_{x→0} cos x = 1 and lim_{x→0} sec x = 1
3. lim_{x→0} (sin⁻¹x)/x = 1 and lim_{x→0} (tan⁻¹x)/x = 1
4. lim_{x→∞} (sin x)/x = 0 [x in radians, sin x bounded, 1/x→0]
5. lim_{x→∞} x·sin(1/x) = 1 [since t = 1/x → 0, expression = sint/t → 1]
6. lim_{x→0} [sin x]/x = 0 [where [ ] = greatest integer function; sin x < x for x > 0, so [sinx/x] = 0 for small x⁺]
7. lim_{x→0} [tan x]/x = 1 [note: tan x > x for 0 < x < π/2, so [tanx/x] = 1]
8. lim_{x→0} cos(x) = 0 [actually lim_{x→0} (cos x)^(1/x) ... from PDF: lim_{x→0} x·cos(x) = 0]
9. lim_{x→0} [tan⁻¹x]/x = 1 [greatest integer of tan⁻¹x/x → ⌊1⌋ = 1]
Note from PDF: sin x < x < tan x for 0 < x < π/2.
Algebraic and exponential standard limits (from PDF — Limits, Continuity and Differentiability JEE Main):
10. lim_{x→a} (xⁿ – aⁿ)/(x – a) = naⁿ⁻¹ for a > 0, n ∈ ℝ; and if a < 0, n ∈ ℤ
11. lim_{x→a} (xⁿ – aⁿ)/(xᵐ – aᵐ) = (n/m)·a^(n–m) [from PDF, follows from formula 10]
12. lim_{x→0} (aˣ – 1)/x = log_e a for a > 0; equivalently lim_{x→0} (eˣ – 1)/x = 1
13. lim_{x→0} log_e(1+x)/x = 1 (= lim_{x→0} ln(1+x)/x) and lim_{x→0} log_a(1+x)/x = log_a e
14. lim_{n→∞} (1 + 1/n)ⁿ = e; lim_{x→0} (1 + x)^(1/x) = e (two equivalent forms of the definition of e)
15. lim_{x→0} (1 + λx)^(1/x) = e^λ for any constant λ; lim_{n→∞} (1 + λ/n)ⁿ = e^λ
Applying standard limits using substitution in Limits, Continuity and Differentiability (JEE Main technique): If lim_{x→a} f(x) = 0 then replace f(x) with u = f(x) → 0 and use: lim sin(f(x))/f(x) = 1; lim (a^f(x) – 1)/f(x) = ln a; lim log(1+f(x))/f(x) = 1. Download the Free PDF for Limits, Continuity and Differentiability for all standard limit applications for JEE Main.
The following expansions from the PDF are used to evaluate limits, find coefficient-of-xⁿ type problems, and connect to the Binomial Theorem and Sequences chapters in JEE Main.
Complete expansion list from PDF — Limits, Continuity and Differentiability:
1. aˣ = 1 + x(ln a) + x²(ln a)²/2! + x³(ln a)³/3! + … for a > 0 (from PDF, general exponential)
2. eˣ = 1 + x/1! + x²/2! + x³/3! + … (valid for all x ∈ ℝ)
3. ln(1+x) = x – x²/2 + x³/3 – x⁴/4 + … (–1 < x ≤ 1) [from PDF, note log = ln = log_e]
4. sin x = x – x³/3! + x⁵/5! – x⁷/7! + …
5. cos x = 1 – x²/2! + x⁴/4! – x⁶/6! + …
6. tan x = x + x³/3 + 2x⁵/15 + … (for |x| < π/2)
7. sin⁻¹x = x + (1²/3!)x³ + (1²·3²/5!)x⁵ + … = x + x³/6 + 3x⁵/40 + … (|x| ≤ 1) [from PDF]
8. tan⁻¹x = x – x³/3 + x⁵/5 – x⁷/7 + … (|x| ≤ 1)
9. (1+x)ⁿ = 1 + nx + n(n–1)x²/2! + … (generalised Binomial, |x| < 1)
Using expansions to evaluate limits (Limits, Continuity and Differentiability — JEE Main method): Substitute the expansion for each function, cancel common factors, and take the limit as x → 0. Example: lim_{x→0} (sinx – x)/x³ = lim_{x→0} [(x – x³/6 + …) – x]/x³ = lim_{x→0} (–x³/6 + …)/x³ = –1/6. This method works for any 0/0 limit involving standard functions at x → 0. The expansion method from Limits, Continuity and Differentiability is faster than L'Hospital's for many JEE Main questions. Download the Free PDF for all expansion-based limit examples.
The 1^∞ indeterminate form in Limits, Continuity and Differentiability arises when f(x) → 1 and g(x) → ∞ as x → a. Evaluating [f(x)]^g(x) directly gives 1^∞ which is indeterminate.
Two evaluation methods for 1^∞ form (from PDF — Limits, Continuity and Differentiability):
Method (a) — Standard 1^∞ shortcut from PDF: If lim_{x→a} f(x) = 1 and lim_{x→a} g(x) = ∞, then:
lim_{x→a} [f(x)]^g(x) = e^{lim_{x→a} g(x)·[f(x)–1]}
This is the direct 1^∞ formula. Memorise it — it makes 1^∞ problems one-line calculations in JEE Main.
More precisely from PDF: if lim_{x→a} f(x) → 1 and lim_{x→a} g(x) → ∞, then:
lim [f(x)]^g(x) = lim [1 + (f(x)–1)]^g(x) = e^{lim g(x)·(f(x)–1)} (using the standard result lim(1+t)^(1/t) = e)
Method (b) — Logarithm approach from PDF: If lim [f(x)]^g(x) gives 0^∞ or ∞^0 form: take natural log → ln[f(x)^g(x)] = g(x)·ln f(x) → becomes 0×∞ form → convert to 0/0 → apply L'Hospital's → exponentiate to get the answer.
Standard e-form limits in Limits, Continuity and Differentiability (from PDF):
lim_{n→∞} (1 + 1/n)ⁿ = e
lim_{x→0} (1 + x)^(1/x) = e
lim_{x→0} (1 + λx)^(1/x) = e^λ
lim_{x→∞} (1 + λ/x)^x = e^λ
lim_{x→0} [(1+x)^(1/x) – e]/x = –e/2 (2nd order refinement)
Newton-Leibnitz Theorem for limits (from PDF — Limits, Continuity and Differentiability): If k(x) = ∫_{α(x)}^{β(x)} f(t) dt, then k'(x) = f(β(x))·β'(x) – f(α(x))·α'(x). This is used to evaluate limits of the type lim_{x→a} [∫_{α(x)}^{β(x)} f(t)dt] / g(x) where numerator → 0 and denominator → 0. Differentiate numerator (by Newton-Leibnitz) and denominator (by chain rule) and take the limit. Download the Free PDF for Limits, Continuity and Differentiability for 1^∞ form and Newton-Leibnitz examples for JEE Main.
Continuity at a point (from PDF — Limits, Continuity and Differentiability): f(x) is continuous at x = a if: f(a⁻) = f(a⁺) = f(a) = a finite number. Equivalently: lim_{x→a} f(x) exists finitely, f(a) is defined, and lim_{x→a} f(x) = f(a). Formal ε-δ definition from PDF: f is continuous at a if for every ε > 0, there exists δ > 0 such that 0 ≤ |x–a| < δ ⟹ |f(x)–f(a)| < ε.
Continuity in open interval (a, b): f is continuous in (a, b) if it is continuous at every point of (a, b).
Continuity in closed interval [a, b] (from PDF — 3 conditions): (1) f is continuous from the right at x = a: lim_{h→0} f(a+h) = f(a). (2) f is continuous from the left at x = b: lim_{h→0} f(b–h) = f(b). (3) f is continuous at every point of the open interval (a, b).
10 Properties of Continuous Functions (from PDF — Limits, Continuity and Differentiability):
1. If f and g are continuous at x = a, then: f+g, f–g, fg, f/g (if g(a)≠0), kf are all continuous at a.
2. [f(x)]^(m/n) is continuous at x = a, provided it is defined in an interval containing a.
3. If f is continuous at a and g is continuous at f(a), then gof is continuous at a (composition of continuous functions is continuous).
4. If f is continuous at a and g is discontinuous at a, then f+g and f–g are discontinuous at a, but fg may still be continuous at a.
5. If f is continuous at a and f(a) ≠ 0, then there exists an open interval (a–δ, a+δ) such that f(x) has the same sign as f(a) throughout this interval.
6. Intermediate Value Theorem (IVT): If f is continuous on [a, b] and f(a)·f(b) < 0, then there exists at least one c ∈ (a, b) such that f(c) = 0 (root exists between a and b).
7. If f is continuous on [a, b] and k is any real number between f(a) and f(b), then there exists at least one c ∈ (a, b) such that f(c) = k (General IVT).
8. If f is continuous on [a, b], then f is bounded on [a, b] (there exists M such that |f(x)| ≤ M for all x ∈ [a, b]).
9. Every polynomial is continuous at every point of ℝ.
10. Every rational function p(x)/q(x) is continuous at every point where q(x) ≠ 0. Logarithmic, exponential, trigonometric, inverse circular, and absolute value functions are all continuous in their domains.
Types of Discontinuity (from PDF — Limits, Continuity and Differentiability):
Removable discontinuity: LHL = RHL = finite value ≠ f(a) (limit exists but ≠ function value). Can be "removed" by redefining f(a).
Discontinuity of 1st kind (jump discontinuity): LHL ≠ RHL but both exist (both are finite). Cannot be removed. Jump = |RHL – LHL|.
Discontinuity of 2nd kind (infinite discontinuity): At least one of LHL or RHL does not exist or is ±∞. Download the Free PDF for Limits, Continuity and Differentiability for all continuity and discontinuity analysis examples for JEE Main.
Differentiability at a point (from PDF — Limits, Continuity and Differentiability): f(x) is differentiable at x = a if the derivative exists at x = a, which requires:
Left Hand Derivative (LHD): f'(a⁻) = lim_{h→0} [f(a–h) – f(a)] / (–h) = lim_{h→0⁺} [f(a) – f(a–h)] / h
Right Hand Derivative (RHD): f'(a⁺) = lim_{h→0} [f(a+h) – f(a)] / h (h > 0, h → 0)
f(x) is differentiable at x = a iff LHD = RHD (finite and equal). Their common value is f'(a).
Relation between Continuity and Differentiability (from PDF — 4 key results for JEE Main):
1. Differentiability ⟹ Continuity: if f(x) is differentiable at x = a, then f(x) is continuous at x = a.
2. Converse is FALSE: Continuity ⟹ Differentiability is NOT true. f(x) = |x| is continuous everywhere but not differentiable at x = 0.
3. f(x) not differentiable at x = a ⟹ f(x) may or may not be continuous at x = a.
4. f(x) not continuous at x = a ⟹ f(x) NOT differentiable at x = a.
5. From PDF: If LHD and RHD at x = a both exist finitely (even if not equal), then f(x) is continuous at x = a.
Geometric interpretation of differentiability (from PDF): If f(x) is continuous but not differentiable at x = a, it implies a sharp corner or kink at x = a (the tangent is not unique — left and right tangents exist but have different slopes). Examples: y = |x| has a kink at x = 0 (LHD = –1, RHD = +1 ≠ LHD → not differentiable). y = |x²–1| has kinks at x = ±1.
Properties of Differentiable Functions (from PDF — Limits, Continuity and Differentiability):
1. Polynomial, exponential, and constant functions are differentiable at every point of ℝ.
2. Logarithmic and trigonometric functions are differentiable in their domains.
3. Sum, difference, product of differentiable functions is differentiable.
4. Composition of differentiable functions is differentiable (chain rule applies).
5. If f(x) and g(x) are both NOT differentiable at a, their sum f(x)+g(x) and product f(x)·g(x) may still be differentiable at a. (e.g., f(x) = |x| and g(x) = –|x| — both not differentiable at 0, but f+g = 0 IS differentiable.) Download the Free PDF for Limits, Continuity and Differentiability for all differentiability analysis examples for JEE Main.
The following 20 basic differentiation formulas from the Aakash PDF are the building blocks of all differentiation in JEE Main Maths. Every application of the product rule, chain rule, or implicit differentiation uses these as its base.
20 Basic Differentiation Formulas (from PDF — Limits, Continuity and Differentiability):
1. d/dx (sin x) = cos x
2. d/dx (cos x) = –sin x
3. d/dx (tan x) = sec²x
4. d/dx (cot x) = –cosec²x
5. d/dx (sec x) = sec x tan x
6. d/dx (cosec x) = –cosec x cot x
7. d/dx (eˣ) = eˣ
8. d/dx (log_e x) = 1/x (x > 0)
9. d/dx (aˣ) = aˣ · ln a (a > 0)
10. d/dx (sin⁻¹x) = 1/√(1–x²), for –1 < x < 1
11. d/dx (cos⁻¹x) = –1/√(1–x²), for –1 < x < 1
12. d/dx (tan⁻¹x) = 1/(1+x²), for x ∈ ℝ
13. d/dx (cot⁻¹x) = –1/(1+x²), for x ∈ ℝ
14. d/dx (cosec⁻¹x) = –1/(|x|√(x²–1)), for |x| > 1
15. d/dx (sec⁻¹x) = 1/(|x|√(x²–1)), for |x| > 1
16. d/dx (constant) = 0
17. d/dx (xⁿ) = nxⁿ⁻¹, for n ∈ ℝ
18. d/dx (x⁻ⁿ) = –n/x^(n+1) for x ≠ 0 (from PDF, consequence of formula 17)
19. d/dx (log_a x) = (1/x) · log_a e = 1/(x · ln a) for x > 0, a > 0, a ≠ 1
20. d/dx |x| = x/|x| = sgn(x), for x ≠ 0; undefined at x = 0. (from PDF)
Basic differentiation rules (from PDF — Limits, Continuity and Differentiability):
Scalar multiple: d/dx[c·f(x)] = c·f'(x)
Sum/Difference: d/dx[f(x) ± g(x)] = f'(x) ± g'(x)
Product rule: d/dx[f(x)·g(x)] = f'(x)·g(x) + f(x)·g'(x)
Quotient rule: d/dx[f(x)/g(x)] = [f'(x)·g(x) – f(x)·g'(x)] / [g(x)]², g(x) ≠ 0
Download the Free PDF for Limits, Continuity and Differentiability for all 20 basic differentiation formulas with examples for JEE Main.
Chain Rule (from PDF — Limits, Continuity and Differentiability): If y = f(g(x)), then dy/dx = f'(g(x))·g'(x). In terms of intermediate variable: if y = f(t) and t = g(x), then dy/dx = (dy/dt)·(dt/dx). Extended chain rule from PDF: if y = f(g(h(x))), then dy/dx = f'(g(h(x))) · g'(h(x)) · h'(x). The chain rule is the single most-used differentiation tool in JEE Main — every composite function differentiation uses it.
Parametric Differentiation (from PDF — Limits, Continuity and Differentiability): If x = φ(t) and y = ψ(t) (parameter t, φ(t) ≠ 0), then: dy/dx = (dy/dt)/(dx/dt) = ψ'(t)/φ'(t). From PDF remark: d²y/dx² ≠ (d²y/dt²)/(d²x/dt²). The correct formula is: d²y/dx² = d/dx(dy/dx) = [d/dt(dy/dx)]/(dx/dt) = [(d/dt(ψ'(t)/φ'(t)))]/φ'(t).
Logarithmic Differentiation (from PDF — Limits, Continuity and Differentiability): Used for two types: (1) Products and quotients of many functions. (2) f(x)^g(x) type where both base and exponent are functions of x. Method: take ln of both sides, differentiate, solve for dy/dx. From PDF direct rule for [f(x)]^g(x): dy/dx = [f(x)]^g(x) · [g'(x)·ln f(x) + g(x)·f'(x)/f(x)].
Trigonometric substitutions for differentiation (from PDF — Limits, Continuity and Differentiability JEE Main):
1. √(a²–x²) → put x = a sinθ or a cosθ
2. √(a²+x²) → put x = a tanθ or a cotθ
3. √(x²–a²) → put x = a secθ or a cosecθ
4. (a–x)/(a+x) or √((a–x)/(a+x)) → put x = a cos2θ
5. (x–a)/(x+a) → put x = a sec2θ
6. √((a–x)(x–β)) for β < x < a → put x = a sin²θ (from PDF)
7. 2ax–x² = a²–(x–a)² → put x–a = a sinθ
8. (x–α)(β–x) for α < x < β → put x = α cos²θ + β sin²θ (from PDF)
Implicit Differentiation (from PDF — Limits, Continuity and Differentiability): If f(x, y) = 0 defines y as a function of x, differentiate both sides w.r.t. x treating y as a function of x (using chain rule for y-terms), then solve for dy/dx. From PDF note: dy/dx = –(∂f/∂x)/(∂f/∂y) where ∂f/∂x = differentiate treating y constant, ∂f/∂y = differentiate treating x constant.
Differentiation of a function with respect to another function (from PDF): To find d[f(x)]/d[g(x)]: compute f'(x) = df/dx and g'(x) = dg/dx, then d[f(x)]/d[g(x)] = f'(x)/g'(x). This is similar to parametric differentiation.
Differentiation of a determinant (from PDF — Limits, Continuity and Differentiability): If each row of a determinant contains functions of x, differentiate the determinant by differentiating one row at a time (keeping other rows constant) and summing the resulting determinants. Download the Free PDF for all advanced differentiation technique examples for JEE Main.
Derivative of infinite series (from PDF — Limits, Continuity and Differentiability):
Type 1: y = √(g(x) + √(g(x) + √(g(x) + …))). From PDF: express as y = √(g(x) + y) → y² – y = g(x) → differentiate: (2y–1)·dy/dx = g'(x) → dy/dx = g'(x)/(2y–1).
Type 2: y = [g(x)]^([g(x)]^([g(x)]^…)) = [g(x)]^y. From PDF: take log → y·ln g(x) = y·ln g(x)... differentiate: dy/dx = y²·g'(x) / [g(x)·(1 – y·ln g(x))].
Higher Order Derivatives (from PDF — Limits, Continuity and Differentiability): dy/dx = f'(x) is the 1st derivative. d²y/dx² = f''(x) is the 2nd derivative (= d/dx of f'(x)). d³y/dx³ = f'''(x), d⁴y/dx⁴ = f^(iv)(x), etc. Linear combination rule from PDF: (c₁u + c₂v)^(n) = c₁u^(n) + c₂v^(n) where u^(n) = nth derivative.
Leibnitz Formula for nth order derivative of product (from PDF — key JEE Main formula):
(uv)^(n) = Σ_{r=0}^{n} C(n,r) · u^(n–r) · v^(r)
= u^(n)·v + n·u^(n–1)·v' + n(n–1)/2!·u^(n–2)·v'' + … + n·u'·v^(n–1) + u·v^(n)
where u^(0) = u, v^(0) = v, and C(n,r) = n!/(r!(n–r)!) are the binomial coefficients.
nth order derivative formulas (from PDF — Limits, Continuity and Differentiability):
(xᵐ)^(n) = m(m–1)…(m–n+1)·x^(m–n) = ᵐPₙ·x^(m–n); if m = n then (xⁿ)^(n) = n!
(aˣ)^(n) = aˣ·(ln a)ⁿ (a > 0)
(eˣ)^(n) = eˣ (nth derivative of eˣ is eˣ)
(ln x)^(n) = (–1)^(n–1) · (n–1)! / xⁿ (from PDF)
(sin x)^(n) = sin(x + nπ/2)
(cos x)^(n) = cos(x + nπ/2)
Functional equation determining f(x) (from PDF — Limits, Continuity and Differentiability): From PDF example: if f(x+y) = f(x)·f(y), f'(0) = k, then f'(x) = k·f(x) → dy/dx = ky → f(x) = e^(kx). If f(0) = 1: f(x) = e^(kx). Download the Free PDF for all higher order derivative examples and Leibnitz formula applications for JEE Main.
All limit definitions (ε-δ), LHL/RHL existence conditions, all 7 indeterminate forms, all 9 algebra of limits rules, Sandwich theorem, L'Hospital's rule with all 4 notes, all 15 standard limits from PDF (sinx/x, tanx/x, aˣ–1/x, log(1+x)/x, (1+1/n)ⁿ=e, xⁿ–aⁿ/x–a=naⁿ⁻¹, etc.), all 9 important expansions (eˣ, sinx, cosx, tanx, sin⁻¹x, tan⁻¹x, ln(1+x), aˣ, (1+x)ⁿ), 1^∞ form shortcut (e^{limg(f–1)}), Newton-Leibnitz theorem, continuity definition, 3-condition closed interval continuity, all 10 continuity properties, IVT, all 3 types of discontinuity, differentiability definition (LHD/RHD), all 4 continuity-differentiability relations, all 5 differentiability properties, all 20 basic differentiation formulas, 4 basic rules (scalar, sum, product, quotient), chain rule, parametric differentiation, implicit differentiation (–∂f/∂x/∂f/∂y), logarithmic differentiation, all 9 trigonometric substitutions, differentiation w.r.t. another function, determinant differentiation, infinite series derivatives, all 6 nth derivative formulas, and Leibnitz formula are compiled in the Aakash Rapid Revision & Formula Bank PDF — structured for JEE Main maths, Class 12 CBSE, and all engineering entrance exams.
Standard limits are pure recall — guaranteed marks with zero calculation time. The 15 standard limits from this chapter (sinx/x=1, aˣ–1/x=lna, log(1+x)/x=1, (1+1/n)ⁿ=e, xⁿ–aⁿ/x–a=naⁿ⁻¹) appear in JEE Main in a recognisable form. A student who knows all 15 can evaluate them in under 20 seconds each. Five standard limit questions in a JEE Main paper = 5 minutes of work if the formulas are memorised.
The 1^∞ shortcut formula eliminates the need for L'Hospital's in the most common exponential limit. The formula lim[f(x)]^g(x) = e^{lim g(x)·(f(x)–1)} (when f→1, g→∞) converts the most complex-looking exponential limits into a one-line calculation. Students who know this formula never need L'Hospital's for 1^∞ forms.
All 20 differentiation formulas are used in every subsequent calculus chapter. The differentiation formulas for sin, cos, tan, eˣ, ln x, xⁿ, and all 6 inverse functions appear in Applications of Derivatives, Integration (for substitution choice), Differential Equations, and Vector Calculus. Every minute spent mastering these 20 formulas pays interest across the entire JEE Main paper.
Continuity and differentiability analysis is a concept-application question type. The questions "is f(x) differentiable at x = 0?" or "find the value of k that makes f(x) continuous at x = 2" are answered by the definition: check LHD = RHD, or check LHL = RHL = f(a). These are straightforward once the definition is clear and the appropriate limit formulas are applied. Download the Free PDF for Limits, Continuity and Differentiability to have all formulas in one place.
After working through Limits, Continuity and Differentiability using this formula sheet, a student should confidently accomplish the following for JEE Main maths.
For limits: state the ε-δ definition, evaluate LHL and RHL from a given function, apply all 9 algebra of limits rules, identify the indeterminate form and choose the correct resolution method, apply all 15 standard limits by recognition and direct substitution, use the expansion method for 0/0 limits at x→0, apply the 1^∞ shortcut formula, apply L'Hospital's rule for 0/0 and ∞/∞ forms, and apply Newton-Leibnitz theorem for limits involving definite integrals.
For continuity: test continuity at a point using LHL = RHL = f(a), classify any given discontinuity as removable/1st kind/2nd kind, apply IVT to existence problems, identify which standard function classes are always continuous.
For differentiability: compute LHD and RHD from the definition, determine differentiability from a given function's formula or graph, state and apply all 4 relations between continuity and differentiability with examples.
For differentiation: apply all 20 basic differentiation formulas from memory, use chain rule for composite functions, product rule, quotient rule, parametric differentiation, implicit differentiation (–∂f/∂x / ∂f/∂y), logarithmic differentiation, all 9 trig substitutions, apply Leibnitz formula for nth derivative of products, and find nth derivative using the 6 nth-order formulas from the PDF. Download the Free PDF for Limits, Continuity and Differentiability to test all these outcomes.
The Aakash Rapid Revision & Formula Bank PDF for Limits, Continuity and Differentiability captures every result from the 12-page document — limit definitions, algebra rules, all standard limits, expansion series, continuity properties with IVT, all 3 discontinuity types, LHD/RHD definition, all 4 continuity-differentiability relations, all 20 differentiation formulas, every differentiation technique, and Leibnitz formula — in one structured JEE Main maths reference.
Limits, Continuity and Differentiability is not merely a chapter — it is the foundation of the entire calculus syllabus in JEE Main. The concept of a limit, rigorously defined and practically evaluated through standard limits, L'Hospital's rule, expansions, and the 1^∞ shortcut, underpins everything from Integration to Differential Equations. The differentiation formulas and techniques (chain rule, product rule, implicit, log, parametric) are the tools used in all subsequent calculus chapters. Continuity and differentiability analysis is the lens through which functions are classified throughout analysis.
For JEE Main, approach Limits, Continuity and Differentiability in three passes. First, master all 15 standard limits (including the 1^∞ formula and (1+λx)^(1/x) = e^λ). Second, master the three continuity conditions and the four LHD/RHD-based differentiability rules. Third, master all 20 differentiation formulas and the five differentiation techniques (chain, product, quotient, implicit, log). Use this page and the Free PDF Download for Limits, Continuity and Differentiability as your complete JEE Main revision foundation.
In Limits, Continuity and Differentiability, the limit lim_{x→a} f(x) exists if and only if the Left Hand Limit (LHL) and Right Hand Limit (RHL) both exist, are equal, and are finite. LHL = lim_{x→a⁻} f(x) = lim_{h→0⁺} f(a–h). RHL = lim_{x→a⁺} f(x) = lim_{h→0⁺} f(a+h). If LHL = RHL = L (finite), then lim_{x→a} f(x) = L. If LHL ≠ RHL, or either is ±∞ or doesn't exist, then the limit does not exist. The function value f(a) is completely irrelevant to the existence of the limit — the limit depends only on the behaviour of f(x) for x near a, not at a itself. This is why lim_{x→0} sinx/x = 1 even though sinx/x is undefined at x=0 (0/0 form). In Limits, Continuity and Differentiability, the limit exists means approaching from both sides gives the same finite value.
The standard limits in Limits, Continuity and Differentiability from the Aakash PDF are: (1) lim_{x→0} sinx/x = 1; (2) lim_{x→0} tanx/x = 1; (3) lim_{x→0} cosx = 1; (4) lim_{x→0} sin⁻¹x/x = 1; (5) lim_{x→0} tan⁻¹x/x = 1; (6) lim_{x→∞} sinx/x = 0; (7) lim_{x→∞} x·sin(1/x) = 1; (8) lim_{x→0} [sinx]/x = 0 (greatest integer function); (9) lim_{x→0} [tanx]/x = 1; (10) lim_{x→a} (xⁿ–aⁿ)/(x–a) = naⁿ⁻¹; (11) lim_{x→a} (xⁿ–aⁿ)/(xᵐ–aᵐ) = (n/m)·a^(n–m); (12) lim_{x→0} (aˣ–1)/x = ln a; (13) lim_{x→0} ln(1+x)/x = 1; (14) lim_{n→∞} (1+1/n)ⁿ = e and lim_{x→0} (1+x)^(1/x) = e; (15) lim_{x→0} (1+λx)^(1/x) = e^λ. All trigonometric standard limits assume x is in radians. The substitution technique: whenever f(x)→0, replace f(x) with t in any standard limit formula.
In Limits, Continuity and Differentiability, the 1^∞ form arises when f(x) → 1 and g(x) → ∞. The shortcut formula from the Aakash PDF is: lim_{x→a} [f(x)]^g(x) = e^{lim_{x→a} g(x)·(f(x)–1)} (when f→1 and g→∞). This works because [f(x)]^g(x) = [1+(f(x)–1)]^g(x), and using the standard result lim(1+t)^(1/t) = e with t = f(x)–1 → 0: the expression → e^{lim g(x)·t} = e^{lim g(x)·(f(x)–1)}. Example: lim_{x→0} (cosx)^(1/x²). f(x) = cosx → 1; g(x) = 1/x² → ∞. g(x)·(f(x)–1) = (cosx–1)/x² = (–x²/2+…)/x² → –1/2. Answer = e^(–1/2). Another example: lim_{x→0} (1+sinx)^(cotx). f=1+sinx→1; g=cotx→∞. g(f–1) = cotx·sinx = cosx → 1. Answer = e¹ = e. The 1^∞ formula eliminates the need for L'Hospital's rule in these cases and is faster for JEE Main Limits Continuity Differentiability questions.
In Limits, Continuity and Differentiability, continuity and differentiability are related but not equivalent. A function f(x) is continuous at x = a if lim_{x→a} f(x) = f(a) (limit exists, function is defined, both are equal). A function is differentiable at x = a if LHD = RHD (both exist and are equal and finite). The key relationships from the Aakash PDF: (1) Differentiability implies Continuity: if f is differentiable at a, it is continuous at a. (2) Continuity does NOT imply Differentiability: f(x) = |x| is continuous at x=0 but not differentiable (LHD = –1, RHD = +1). (3) If f is not differentiable at a, it may or may not be continuous at a. (4) If f is not continuous at a, it is definitely not differentiable at a. (5) If both LHD and RHD exist finitely (even if not equal), then f is continuous. Geometrically: continuity means the graph has no breaks; differentiability means no breaks AND no sharp corners or kinks (smooth curve with a unique tangent at every point).
In Limits, Continuity and Differentiability, discontinuities are classified into three types: (1) Removable discontinuity: LHL = RHL = a finite value, but f(a) is either undefined or ≠ LHL = RHL. The limit exists but is not equal to the function value. Can be "removed" by redefining f(a) = L. Example: f(x) = sinx/x — limit at x=0 is 1, but f(0) is undefined; define f(0) = 1 to make it continuous. (2) Discontinuity of the 1st kind (Jump discontinuity): LHL ≠ RHL, but both exist as finite values. The jump = |RHL – LHL|. Cannot be removed by redefining f(a). Example: f(x) = [x] (greatest integer function) at any integer — LHL and RHL both exist but differ by 1. (3) Discontinuity of the 2nd kind (Infinite/Essential discontinuity): at least one of LHL or RHL does not exist (is ±∞ or oscillates). Example: f(x) = 1/x at x=0 (LHL = –∞, RHL = +∞); f(x) = sin(1/x) at x=0 (limit doesn't exist — oscillates). These three discontinuity type classifications from Limits, Continuity and Differentiability appear directly in JEE Main questions.
L'Hospital's Rule in Limits, Continuity and Differentiability states: if lim_{x→a} f(x)/g(x) gives the 0/0 or ∞/∞ indeterminate form (where both f(a)=0 and g(a)=0, or both →∞), then lim f(x)/g(x) = lim f'(x)/g'(x) (differentiate numerator and denominator separately, NOT using the quotient rule). Key notes from the Aakash PDF: (1) Differentiate numerator and denominator independently. (2) Apply repeatedly until the indeterminate form disappears. (3) Also applies for x→∞. (4) For 0×∞ form: rewrite as f(x)/[1/g(x)] (=0/0) or g(x)/[1/f(x)] (=∞/∞), then apply. (5) For ∞–∞ form: find common denominator (LCM) to convert to 0/0 or ∞/∞. (6) For 1^∞, 0⁰, ∞⁰: take logarithm → becomes 0×∞ → convert to 0/0 → apply L'Hospital's. The expansion method is often faster than L'Hospital's for polynomial-type 0/0 limits at x→0 — choose whichever is quicker for each JEE Main question in Limits Continuity Differentiability.
The 20 basic differentiation formulas from the Aakash PDF: d/dx(sinx)=cosx; d/dx(cosx)=–sinx; d/dx(tanx)=sec²x; d/dx(cotx)=–cosec²x; d/dx(secx)=secx·tanx; d/dx(cosecx)=–cosecx·cotx; d/dx(eˣ)=eˣ; d/dx(ln x)=1/x (x>0); d/dx(aˣ)=aˣ·lna (a>0); d/dx(sin⁻¹x)=1/√(1–x²) for |x|<1; d/dx(cos⁻¹x)=–1/√(1–x²) for |x|<1; d/dx(tan⁻¹x)=1/(1+x²) for x∈ℝ; d/dx(cot⁻¹x)=–1/(1+x²) for x∈ℝ; d/dx(sec⁻¹x)=1/(|x|√(x²–1)) for |x|>1; d/dx(cosec⁻¹x)=–1/(|x|√(x²–1)) for |x|>1; d/dx(constant)=0; d/dx(xⁿ)=nxⁿ⁻¹ for n∈ℝ; d/dx(log_ax)=1/(x·lna); d/dx|x|=x/|x|=sgn(x) for x≠0. Key observations: d/dx(sin⁻¹x)+d/dx(cos⁻¹x)=0 (since their sum is π/2, constant); d/dx(tan⁻¹x)+d/dx(cot⁻¹x)=0; d/dx(sec⁻¹x)+d/dx(cosec⁻¹x)=0. The inverse trig pairs are always negatives of each other.
Parametric differentiation in Limits, Continuity and Differentiability is used when x and y are both expressed as functions of a third parameter t: x = φ(t), y = ψ(t). Then dy/dx = (dy/dt)/(dx/dt) = ψ'(t)/φ'(t). For the second derivative d²y/dx², the important note from the Aakash PDF is: d²y/dx² ≠ (d²y/dt²)/(d²x/dt²). The correct formula: d²y/dx² = d/dx(dy/dx) = [d/dt(dy/dx)] / (dx/dt). Step 1: find dy/dx = ψ'(t)/φ'(t) = p(t) (a function of t). Step 2: differentiate p(t) with respect to t: dp/dt. Step 3: divide by dx/dt = φ'(t): d²y/dx² = [dp/dt]/φ'(t) = [d/dt(ψ'(t)/φ'(t))]/φ'(t). Example: x = sinθ, y = cosθ. dy/dx = (–sinθ)/(cosθ) = –tanθ. d²y/dx²: d/dθ(–tanθ) = –sec²θ. Divide by dx/dθ = cosθ: d²y/dx² = –sec²θ/cosθ = –sec³θ. This parametric differentiation method is used in curve analysis and JEE Main Limits Continuity Differentiability problems involving conics in parametric form.
Leibnitz formula in Limits, Continuity and Differentiability gives the nth derivative of a product of two functions u and v: (uv)^(n) = Σ_{r=0}^{n} C(n,r) · u^(n–r) · v^(r) = u^(n)v + nu^(n–1)v' + n(n–1)/2!·u^(n–2)v'' + … + nuv^(n–1) + uv^(n). Here C(n,r) = n!/(r!(n–r)!) are binomial coefficients, and u^(k) denotes the kth derivative of u. The formula is a direct parallel to the Binomial Theorem: (u+v)ⁿ expansion maps to (uv)^(n) by replacing powers with derivatives. Key nth derivative formulas for applying Leibnitz: (sinx)^(n) = sin(x+nπ/2); (cosx)^(n) = cos(x+nπ/2); (eˣ)^(n) = eˣ; (eᵃˣ)^(n) = aⁿeᵃˣ; (xᵐ)^(n) = m!/(m–n)! · x^(m–n) for m≥n; = 0 for m < n (polynomial of degree m has (m+1)th and higher derivatives = 0). (ln x)^(n) = (–1)^(n–1)(n–1)!/xⁿ. Leibnitz formula application: find (x²·sinx)^(n) by taking u=x², v=sinx and applying the formula with u^(3)=0 (degree 2 polynomial has 3rd and higher derivatives = 0).
Newton-Leibnitz theorem in Limits, Continuity and Differentiability states: if k(x) = ∫_{α(x)}^{β(x)} f(t) dt, then the derivative is k'(x) = f(β(x))·β'(x) – f(α(x))·α'(x). The upper limit's contribution is f(evaluated at upper limit) × derivative of upper limit; lower limit contributes the negative. This theorem is used in JEE Main Limits, Continuity and Differentiability to evaluate limits of the type: lim_{x→a} [∫_{α(x)}^{β(x)} f(t)dt] / g(x) where this takes the 0/0 form. Apply L'Hospital's: differentiate the numerator using Newton-Leibnitz and the denominator normally. Example: lim_{x→0} [∫_0^x sin(t²)dt]/x³. Applying L'Hospital: numerator derivative = sin(x²)·1 = sin(x²); denominator derivative = 3x². Still 0/0. Apply again: sin(x²)/(3x²). Use standard limit sin(x²)/x² → 1: → 1/3. Final answer = 1/3. Newton-Leibnitz theorem also appears in JEE Advanced as a differentiation tool for integral-defined functions where the limits of integration are functions of x.
Limits, Continuity and Differentiability – JEE Main Maths Formula Sheet