Ans: (a) $(3m+2n)(m-n)$ (b) $(m-n)(3m+2n-1)$
-
$\begin{array}{cl}
& 3m^2-mn-2n^2 \\
= & (3m+2n)(m-n)
\end{array}$ -
$\begin{array}{cl}
& 3m^2-mn-2n^2-m+n \\
= & (3m+2n)(m-n) – (m-n) \\
= & (m-n)(3m+2n-1)
\end{array}$
