Question 185284
Is the inverse function yields -1 when given -12 as input, then the original function yields -12 when given -1 as input.
So 
{{{f(x)=k(x^3+x-2)}}}
{{{-12 = k((-1)^3 -1 - 2)}}}
{{{-12 = k (-4)}}}
{{{k = 3}}}