Suppose $2-p, p, 2-\alpha, \alpha$ are the coefficients of four consecutive terms in the expansion of $(1+x)^n$. Then the value of $p^2-\alpha^2+6 \alpha+2 p$ equals
Solution
<p>$2-p, p, 2-\alpha, \alpha$</p>
<p>Binomial coefficients are</p>
<p>$$\begin{aligned}
& { }^n C_r,{ }^n C_{r+1},{ }^n C_{r+2},{ }^n C_{r+3} \text { respectively } \\
\Rightarrow \quad & { }^n C_r+{ }^n C_{r+1}=2 \\
\Rightarrow \quad & { }^{n+1} C_{r+1}=2 \quad \ldots . .(1)
\end{aligned}$$</p>
<p>Also, $${ }^{\mathrm{n}} \mathrm{C}_{\mathrm{r}+2}+{ }^{\mathrm{n}} \mathrm{C}_{\mathrm{r}+3}=2$$</p>
<p>$\Rightarrow \quad{ }^{n+1} C_{r+3}=2$ $\quad\text{..... (2)}$</p>
<p>From (1) and (2)</p>
<p>$$\begin{aligned}
& { }^{n+1} C_{r+1}={ }^{n+1} C_{r+3} \\
& \Rightarrow \quad 2 \mathrm{r}+4=\mathrm{n}+1 \\
& \mathrm{n}=2 \mathrm{r}+3 \\
& { }^{2 \mathrm{r}+4} \mathrm{C}_{\mathrm{r}+1}=2 \\
\end{aligned}$$</p>
<p>Data Inconsistent</p>
About this question
Subject: Mathematics · Chapter: Binomial Theorem · Topic: Binomial Expansion
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