\(1,\Leftrightarrow\left(x-y\right).\left(x+y\right)+4\left(x-y\right)\)

\(\Leftrightarrow\left(x-y\right).\left(x+y+4\right)\)

\(2,\Leftrightarrow x^2+x-7x-7\)

\(\Leftrightarrow x.\left(x+1\right)-7\left(x+1\right)\)

\(\Leftrightarrow\left(x+1\right).\left(x-7\right)\)

\(3\Leftrightarrow2x.\left(x^2-4x+4\right)\)

\(\Leftrightarrow2x.\left(x-2\right)^2\)

\(4,\Leftrightarrow2x^2+5x-2x-5\)

\(\Leftrightarrow x.\left(2x+5\right)-\left(2x+5\right)\)

\(\Leftrightarrow\left(2x+5\right).\left(x-1\right)\)

A