I've got two equations containing a function in z and 3 constants:

f(z) + 2AB + B - z^2 = 0 and

-Az^3 +(2A-B)Z^2 + Z(2f(Z) + 2B - C) - 2C

These equations have arisen from a fluid mechanics problem, but how would I solve them to find f(z)?

(when I do it I find f(z) to be a constant when it should be a function of z)