A) 4
B) \[2\sqrt{2}\]
C) 3
D) \[\sqrt{5}\]
Correct Answer: A
Solution :
\[{{T}_{r+1}}{{=}^{10}}Cr(\sqrt{x}){{\,}^{10-r}}\,{{\left( \frac{\lambda }{{{x}^{2}}} \right)}^{r}}\,={{\,}^{10}}Cr\,{{\lambda }^{r}}\,{{x}^{5-\frac{r}{2}-2r}}\,\] \[\Rightarrow \,\,\,5-\frac{r}{2}\,-\,2r=0\,\,\,\Rightarrow \,\,\,r=2\] coefficient of \[{{x}^{2}}\Rightarrow \,{{\,}^{10}}{{C}_{2}}{{\lambda }^{2}}=720\,\,\Rightarrow \,{{\lambda }^{2}}=16\] \[\Rightarrow \,\,\lambda \,\,=\pm \,\text{4}\,\,\,\Rightarrow \,\,\lambda \,\,\Rightarrow \,\,4\]You need to login to perform this action.
You will be redirected in
3 sec