If the coefficient of $(2 r+1)$ th term and $(r+2)$ th term in the expansion of $(1+x)^{43}$ are equal, then $r$ is equal to :

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Aicharya · Accepted Answer

Given that, Coefficient of $(2 r+1)$ th term $=$ co-efficient of $(r+2)$ th term $\Rightarrow \quad{ }^{43} C_{2 r}={ }^{43} C_{r+1}$ $\Rightarrow \quad 2 r+(r+1)=43$ or $\quad 2 r=r+1$ $\Rightarrow \quad r=14$ or $r=1$ thus $r=14$

If the coefficient of $(2 r+1)$ th term and $(r+2)$ th term in the expansion of $(1+x)^{43}$ are equal, then…

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