please help me solve these question, simlify: (x^4-y^4)/(x^3-y^3)
ya gotta do a bunch of these, till you can easily recognize differences of squares and cubes
x^4-y^4 = (x^2-y^2)(x^2+y^2) = (x-y)(x+y)(x^2+y^2)
x^3-y^3 = (x-y)(x^2+xy+y^2)
divide, and the (x-y)'s cancel, leaving
(x+y)(x^2+y^2) / (x^2+xy+y^2)