If $\displaystyle h(x) = x^n / k$ and $\displaystyle k$ is a nonzero constant and $\displaystyle n$ is an integer, find the values of $\displaystyle k$ and $\displaystyle n$ so that where x=2, the value of h(x) is equal to 8 and the slope of the graph of the same function is -4

Would i first solve the derivative and work from there? Thanks!