Question:
Write the general term in the expansion of
$\left(x^{2}-y\right)^{6}$
Solution:
To Find : General term, i.e. $t_{r+1}$
For $\left(x^{2}-y\right)^{6}$
$a=x^{2}, b=-y$ and $n=6$
General term $t_{r+1}$ is given by,
$\mathrm{t}_{\mathrm{r}+1}=\left(\begin{array}{l}\mathrm{n} \\ \mathrm{r}\end{array}\right) \mathrm{a}^{\mathrm{n}-\mathrm{r}} \mathrm{b}^{\mathrm{r}}$
$=\left(\begin{array}{l}6 \\ r\end{array}\right)\left(x^{2}\right)^{6-r}(-y)^{r}$
$\underline{\text { Conclusion : General term }}=\left(\begin{array}{l}6 \\ \mathrm{r}\end{array}\right)\left(\mathrm{x}^{2}\right)^{6-\mathrm{r}}(-\mathrm{y})^{\mathrm{r}}$