JEE Mains · Maths · STD 11 - 7. binomial theoram
If \(\sum_{r=1}^{30} \frac{r^2\left({ }^{30} C_r\right)^2}{{ }^{30} C_{r-1}}=\alpha \times 2^{29}\), then \(\alpha\) is equal to ______
- A 400
- B 465
- C 542
- D 425
Answer & Solution
Correct Answer
(B) 465
Step-by-step Solution
Detailed explanation
\begin{aligned} & \sum_{\mathrm{r}=1}^{30} \frac{\mathrm{r}^2\left({ }^{30} \mathrm{C}_{\mathrm{r}}\right)^2}{{ }^{30} \mathrm{C}_{\mathrm{r}-1}} \\ & =\sum_{\mathrm{r}=1}^{30} \mathrm{r}^2\left(\frac{31-\mathrm{r}}{\mathrm{r}}\right) \cdot…
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