4 4 a - b
a^4 - b^4
1*(a + b)*(a - b)*(a + I*b)*(a - I*b)
(((1*(a + b))*(a - b))*(a + i*b))*(a - i*b)
/ 2 2\ (a + b)*(a - b)*\a + b /
(a + b)*(a - b)*(a^2 + b^2)