JEE PYQ

[JEE Advanced 1989] prove that c 0 2 2c 1 3 2c 2 1 n n 1

VAVidaara Admin Asked 2d ago 0 views 1 answer

Prove that $C_0-2^2C_1+3^2C_2-\cdots+(-1)^n(n+1)^2C_n=0$ for $n>2$.

1 Answer

VAVidaara Admin ✓ Vidaara Team ✓ Accepted · 2d ago ▲ 0

Answer: Proved.

Writing $(r+1)^2=r(r-1)+3r+1$ and using $\sum(-1)^r\binom nr=0$, $\sum(-1)^r r\binom nr=0$, $\sum(-1)^r r(r-1)\binom nr=0$ (all $0$ for $n>2$) gives the result.

JEE Advanced 1989 · Binomial Theorem — verified solution by the Vidaara Team.

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