Determine the equation of the tangent to y= f(x) at the point where x= -1.
The point of tangency is (-1,f(-1))
The slope is f'(-1)
So the line has equation
y-f(-1) = f'(-1) (x+1)
The slope is f'(-1)
So the line has equation
y-f(-1) = f'(-1) (x+1)