5 5 a - b ------- a + b
(a^5 - b^5)/(a + b)
5 4 4 2 2 3 3 2*b a + b + a *b - a*b - b*a - ----- a + b
/ 4 4 3 3 2 2\ (a - b)*\a + b + a*b + b*a + a *b / --------------------------------------- a + b