

InterviewSolution
Saved Bookmarks
1. |
In the binomial expansion of `(a+b)^n`, the coefficient of the 4th and 13th terms are equal to each other. Find n |
Answer» General term in `(a+b)^n,(T_(r+1)) = C(n,r)a^(n-r)b^r ` `:. T_4 = C(n,3)a^(n-3)b^3` `T_13 = C(n,12)a^(n-12)b^12` We are given coefficients of 4th and 13th terms are equal to each other. `:. C(n,3) = C(n,12)` We know, `C(n,12) = C(n,(n-12))` `:. C(n,3) = C(n,(n-12))` `=> 3 = n-12` `=> n = 15` |
|