a(x) = x^(2.0)
b(x) = 2.0 * x * (x + 4.0)
c(x) = (x + 2.0) * (x + 3.0)
d(x) = (x + 3.0) * (x + 3.0)
e(x) = x * (4.0 - x)
f(x) = x * (x - 4.0)
g(x) = x * (x + 4.0)
i(x) = (x + 3.0) * (x - 3.0)