jee-main 2023 Q67

jee-main · India · session1_31jan_shift2 Permutations & Arrangements Factorial and Combinatorial Expression Simplification

If ${}^{2n+1}P_{n-1} : {}^{2n-1}P_n = 11 : 21$, then $n^2 + n + 15$ is equal to $\_\_\_\_$.

If ${}^{2n+1}P_{n-1} : {}^{2n-1}P_n = 11 : 21$, then $n^2 + n + 15$ is equal to $\_\_\_\_$.