If the coefficients of xr−1,xr and xr+1 in the binomial expansion of – InterviewSolution

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1.	If the coefficients of xr−1,xr and xr+1 in the binomial expansion of (1+x)n are in AP, prove that n2−n(4r+1)+4r2−2=0
Answer» If the coefficients of $x^{r - 1}, x^{r}$ and $x^{r + 1}$ in the binomial expansion of $(1 + x)^{n}$ are in AP, prove that $n^{2} - n (4 r + 1) + 4 r^{2} - 2 = 0$

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