Question:
The position of the term independent of $x$ in the expansion of $\left(\sqrt{\frac{x}{3}}+\frac{3}{2 x^{2}}\right)^{10}$ is _____________
Solution:
for $\left(\sqrt{\frac{x}{3}}+\frac{3}{2 x^{2}}\right)^{10}$
$T_{r+1}={ }^{10} C_{r}\left(\sqrt{\frac{x}{3}}\right)^{10-r}\left(\frac{3}{2 x^{2}}\right)^{r}$
$={ }^{10} C_{r} \frac{1}{(\sqrt{3})^{10-r}} x^{\frac{10-r}{2}} x^{-2 r}\left(\frac{3}{2}\right)^{r}$
$T_{r+1}=\frac{{ }^{10} C_{r}}{(\sqrt{3})^{10-r}}\left(\frac{3}{2}\right)^{r} \quad x^{\frac{10-5 r}{2}}$
for constant term, $\frac{10-5 r}{2}=0 \quad$ i. e. $r=2$
Hence, third term is independent of x.