supose that the random variable X is uniformly distributed between x=-4 and x=2 Y=9-X^2

whats the Y probability distribution?

My main problem here are the bounds how do I set the bounds? I think I have two values for the distribution between y=5 and y=9, since I have to split it in two problems, one in which dy/dx is positive and other where it is negative, and whad do I do with the point where dy/dx =0?!