2 2 16*z z - 4*z + ----- 16
z^2 - 4*z + (16*z^2)/16
-4*z + 2*z^2
2 -4*z + 2*z
x*(x - 2)
2*z*(-2 + z)
2.0*z^2 - 4.0*z
2 -64*z + 32*z ------------- 16
(-64*z + 32*z^2)/16