MCQ
Find the coefficient of $\frac{1}{\text{y}^{2}}$​ in $\Big(\text{y}+\frac{\text{c}}{\text{y}^{2}}\Big)^{10}.$
  • $ 210 c^4 $
  • B
    $ 210 c^5 $
  • C
    $ 120 c^3 $
  • D
    $ 120 c^4 $

Answer

Correct option: A.
$ 210 c^4 $
$\Big(\text{y}+\frac{\text{c}}{\text{y}^{2}}\Big)^{10}$
$\text{T}_{\text{r}+1}={^{10}}\text{C}_{\text{r}}\text{y}^{10-3\text{r}}\text{c}^{\text{r}}$
 Hence for $y^{-2}$
$10-3 r=-2$
$12=3 r$
$r=4$
Coefficient will be
${ }^{10} \mathrm{C}_4 \mathrm{c}^4$
$=210 \mathrm{c}^4$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free