Simplify: (x+y)4−4xy(x+y)2+4x2y2(x+y)^4 - 4xy(x+y)^2 + 4x^2y^2(x+y)4−4xy(x+y)2+4x2y2. Hint: let s=x+ys=x+ys=x+y and p=xyp=xyp=xy.
(x−y)4(x-y)^4(x−y)4
(x+y)4(x+y)^4(x+y)4
(x2−y2)2(x^2-y^2)^2(x2−y2)2
4(x−y)24(x-y)^24(x−y)2