Show that the line 4x-y+11=0 is tangent to the curve y=16/x^2 -1

What I have so far:

I found out that the slope of the linear function is m=4

Then I found the derivative of the curve which ended up to be

y'=-32x^(-3)

so now what should I do with this to show that the line 4x-y+11=0 is tangent to the curve?