$\sqrt{1.5625} = ?$

The smallest number which when subtracted from the number $62512$ makes it a perfect square is

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

The largest among the numbers $\sqrt{7}-\sqrt{5}$,$\sqrt{5}-\sqrt{3}$,$\sqrt{9}-\sqrt{7}$,and $\sqrt{11}-\sqrt{9}$ is:

$1.5^{2} \times \sqrt{0.0225} = ?$

If $x=\frac{\sqrt{3}+1}{\sqrt{3}-1}$ and $y=\frac{\sqrt{3}-1}{\sqrt{3}+1},$ then the value of $(x^{2}+y^{2})$ is