\[2x + 7y + 14 + xy =\]
\[= 2x + 14 + xy + 7y =\]
\[= 2 \cdot (x + 7) + y(x + 7) =\]
\[= (x + 7)(2 + y)\]
\[Проверка:\]
\[(x + 7)(2 + y) =\]
\[= 2x + 7y + 14 + xy\]
\[\Longrightarrow верно.\]