$\"\"$

\

The expression is $\"\"$ and the value of $\"\"$ .

\

Substitute the value of $\"\"$ in the expression $\"\"$ .

\

$\"\"$

\

Rewrite the value of $\"\"$ as 81.

\

$\"\"$

\

Cancel the square and square root.

\

$\"\"$

\

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

\

The value of expression is 18.