Step 2:
First, let's check if $f_{X,Y}(x, y) \ge 0$. Since $x > 1$ and $y > 1$, $x^2 > 0$ and $y^2 > 0$, so $x^2y^2 > 0$. Therefore, $f_{X,Y}(x, y) = \frac{4}{x^2y^2} > 0$ for $1 < x < 2$ and $1 < y < 2$.
Step 3:
Now let's check if the integral is equal to 1:
$$
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