Given:

We will find the equation of the line tangent to f(x) at the point (0, -9)
the slope of the tangent line = the first derivative f'(x)
the first derivative will be as follows:

substitute x = 0 to find the slope of the line tangent at (0,-9)

So, the equation of the line will be: y = x - 9
so, the answer will be:
m = 1
b = -9