Ans: (a) $ab(a+b)$ (b) $(a+b)(ab+7)$
-
$\begin{array}{cl}
& a^2b+ab^2 \\
= & ab(a+b)
\end{array}$ -
$\begin{array}{cl}
& a^2b+ab^2+7a+7b \\
= & ab(a+b) +7a + 7b \\
= & ab(a+b) +7(a+b) \\
= & (a+b)(ab+7)
\end{array}$
