The even function of the following is

If f(x + 2y, x $$-$$ 2y) = xy, then f(x, y) is equal to

If $g(f(x))=|\sin x|$ and $f(g(x))=(\sin \sqrt{x})^2$, then

If $f(x)=\frac{3 x-4}{2 x-3}$, then $f(f(f(x)))$ will be