F(x)=k(2-x-x^3) has an inverse function, and f^-1(3)=-2, FIND K

f^-1 ( x) = y means that f(y) = x, so we know that f(-2) = 3.

Compute f(-2) = k(2 - - 2 - (-2)^3) = k(2 + 2 + 8) = 12k

So 12k = 3
k = 3/12 = 1/4

f(-2) = 3 ---> k = ...