4 2 2 4 x + a *x + a --------------- 1 / 1\ |/ 3 3\ | \\x + a / /
4 4 2 2 a + x + a *x --------------- 3 3 a + x
(a^4 + x^4 + a^2*x^2)/(a^3 + x^3)
4 2 / 2 2\ a + x *\a + x / ----------------- 3 3 a + x
2 2 a + x + a*x ------------- a + x
2 a x + ----- a + x