$\"\"$

\

The expression is $\"\"$ .

\

If $\"\"$ , where b,d $\"\"$ .

\

$\"\"$

\

$\"\"$ (Can be write $\"\"$ )

\

$\"\"$ (Cancel common terms)

\

$\"\"$ (Multiply numerator: $\"\"$ ) $\"\"$

\

The product is $\"\"$ .