# RD Sharma Solutions for Class 11 Maths Chapter 17: Combinations

We've previously looked at how to organise items by taking any or all of them at once. A combination in mathematics is a fusion of several choices created by taking any or all of a set of items, regardless of their arrangement. Two theorems define the link between the two concepts in permutation and combination for class 11. They include:

• nPr = nCr r! (if 0 < r ≤ n).
• nCr + nCr-1 = n+1Cr

There are some key characteristics of combination in all, which make solving many combination problems simple. In addition, the notion of combination has yielded a few extremely important outcomes. This idea aids in determining the distribution of entities or the selection of an item, as well as their proper placement. The following are some of the most notable geometric findings of combination:

• The number of line segments created equals nC2 if there are n unique points in the plane, none of which are collinear.
• The number of line segments is (nC2mC2 + 1) if there are 'm' number of collinear points.
• The number of triangles formed equals nC3 when there are n unique plane points, none of which are collinear.
• The number of triangles formed equals nC3mC3 when there are n unique points on a plane, of which m are collinear.

The chapter is very important because the concepts taught here are used along with the permutation concepts to solve probability and statistics problems. All four topics are then used in the sciences of analytics and forecasting. First, the chapter builds upon the concepts covered in the chapter on permutation. Second, the chapter majorly focuses on Combinations, and the characteristics of  nCr are explained thoroughly in this chapter. Third, combination issues in practice are mentioned in the RD Sharma Solutions. Finally, permutations and variations as mixed problems finish all the topics related to this chapter.

Students who choose to learn independently and solve the exercise problems can use the RD Sharma Class 11 Maths Solutions as a guide book, which is the best resource available. Tutors produce all of the options with the new CBSE labelling trends in mind.