Hello guys, this is one of the question from our exams and I did try to solve it but I was still dubious of my answer. I want to see other answers and strategy in approaching the problem. Thank you

Prove that x^2y^2(4-x^2)(4-y^2)<(or equal)16 is always true for the values of Absolute(x)<(or equal)2 and absolute(y)<(or equal)2.... so I guess the intervals are all [0 2]......