JEE PYQ: Binomial Theorem Question 19
Question 19 - 2020 (02 Sep Shift 2)
For a positive integer $n$, $\left(1+\frac{1}{x}\right)^n$ is expanded in increasing powers of $x$. If three consecutive coefficients in this expansion are in the ratio $2:5:12$, then $n$ is equal to ____.
Show Answer
Answer: 118
Solution
Solving $2n - 7r + 2 = 0$ and $5n - 17r - 12 = 0$: $n = 118, r = 34$.