I need help with the following problem:

Let S be the region bounded between f(x)=16-x^2 and g(x)=2x+1

Find the x-coordinates of the points of intersection.

I am getting stuck on one step of this problem and am not really sure what to do next. I know that you should begin by setting the two equations equal to each other:

16-x^2=2x+1

-x^2-2x+15=0

When I get to the second step of this problem, I am not really sure what to do next. My calculus book starts to factor in this step, but this problem doesn't look like it can be factored. I am not really sure what I am supposed to do next. If anyone could explain to me how to go about getting the answer to this problem, I would greatly appreciate it. Thanks in advance to anyone who can help me.