$\"\"$

\

The expression is $\"\"$ .

\

The product of two opposite signs is negative.

\

$\"\"$

\

Group the coefficients and variables.

\

$\"\"$

\

The product of two opposite signs is negative.

\

$\"\"$

\

Apply formula: $\"\"$ .

\

$\"\"$ . $\"\"$

\

The value of expression $\"\"$ .