Prove that in a primitive Pythagorean triple x, y, z, the product xy is divisible by 12, hence 60|xyz.
Try to use the following results:
Any pythogorean triple is of the form $\displaystyle x = m^2 - n^2, y = 2mn$ and $\displaystyle z = m^2 + n^2$ where m and n are of different parity.