$\"\"$

\

The expression is $\"\"$ .

\

Compare the binomial expression with $\"\"$

\

Then $\"\"$ .

\

Binomial theorem $\"\"$

\

$\"\"$

\

By using the formula $\"\"$ .

\

$\"\"$

\

$\"\"$

\

$\"\"$ $\"\"$

\

$\"\"$ .