$\sqrt{10} \times \sqrt{250} = ?$

In the following questions,two equations numbered $I$ and $II$ are given. You have to solve both the equations and give the answer.
$I$: $5x^2 - 18x + 9 = 0$
$II$: $3y^2 + 5y - 2 = 0$

$\frac{1}{\sqrt{9}-\sqrt{8}} = ?$

The largest number of five digits which is a perfect square is

$\sqrt{54} \times \sqrt{2120} \div \sqrt{460} = ?$

If $x * y = x + y + \sqrt{xy}$,the value of $6 * 24$ is