
A quadratic equation is an equation of degree 2 in the form ax²+bx+c = 0, where a is not equal to 0. The value of x in this equation is called the roots of the quadratic equation. There are only two roots in a quadratic equation. The nature of these roots can be real and imaginary.
| Value of discriminant | Nature of roots | |
| D > 0 | Real, distinct | |
| D is a perfect square | Rational roots | |
| D is not a perfect square | Irrational roots | |
| D = 0 | Real, equal | |
| D < 0 | Complex, distinct (a pair of complex conjugates) | |
Where D is called the discriminant of the root and is equal to b² – 4ac.
The universal equation to find roots of a quadratic equation ax² + bx + c = 0 is given by:
1. Factorization method: - It is the simplest method to find the roots of a quadratic equation. It is not applicable to all forms of the quadratic equation but is suitable for simple forms.
Example
Find the roots of the quadratic equation x² – 6x + 5 = 0 by factorization method.
Solution
By trial and error, we need to find the factors that make 6x and can be taken common from the terms x² and 5.
The above equation can be written as x² – 5x – x + 5 = 0
This implies, x (x-5) – 1 (x-5) = 0
This gives, (x-5) (x-1) = 0
We get the roots as x = 1 or x = 5.
2. Quadratic formula: - We can use the universal quadratic formula to find the roots of every quadratic equation.
Example
Find the roots of the equation x² – 6x + 5 = 0 from the quadratic formula.
Solution
Compare the given equation with the equation ax² + bx + c = 0.
We get, a = 1, b = -6, c = 5
By putting these values in the universal equation, we get
We get, x = 5 or x = 1, which are the roots of the quadratic equation x² – 6x + 5.
JEE Main marks vs rank vs percentile
JEE Advanced Eligibility Criteria
JEE Advanced Chemistry Syllabus
JEE Advanced Registration Dates
Derivation Of Lens Maker Formula
Unit Of Pressure Velocity Uses of Plane Mirror
Wave Theory of Light
Unit of Density Unit of Light Unit of Force Unit of Magnetic Field Unit of wavelength Unit of Viscosity Uses of Electroplating Young's Modulus
What is the Scattering of Light
Lenz Law Space Wave Propagation Schrodinger Wave Equation Relation between Fahrenheit and Celsius Refractive Index Potentiometer Working Pascal Law Oscillatory Motion Optical Instruments Newton's Laws of Motion - First Law Modulation and Demodulation Magnetic Flux Lens Formula and Magnification Kaleidoscope Faradays Law Epsilon Naught Value Energy Bands Electrostatics Electroscope AC Generator Unit of Current Lithosphere Bending Equation Derivation Difference Between Pound and Kilogram Semiconductor Devices OTEC - Ocean Thermal Energy Conversion Hall Effect Rectilinear Propagation of Light Difference Between Ammeter and Voltmeter Coefficient of Linear Expansion Ampere’s Law Cyclone and Thunderstorm Save The Environment From Pollution Particle Nature of Light Types of DC Motor Uses Of Transistor Derivation of Phase Rule Unit of Humidity