Perfect Square times Perfect Square

Definition: A perfect square looks like $n^2$ where $n \in \Z$

$a^2 \times b^2=a^2b^2=(ab)^2$

$a$ and $b$ must be integers because $a^2$ and $b^2$ are perfect squares.

Since $ab$ is an integer multiplied by an integer which always results in another integer, $\boxed{ (ab)^2 \textrm{ must always be a perfect square!} }$

$x^2 \times y^2 = (xy)^2 = x^2y^2$

Therefore, it is true.

$x^{2}$ $\times$ $y^{2}$ = $(xy)^2$ which is a perfect square. Hence, the statement is true