Respuesta :

Answer:

f'(x)=-(x+42)/5

Step-by-step explanation:

Rewrite f(x) as y:

y=-5x-42

Flip x and y and solve for y:

x=-5y-42

x+42=-5y

(x+42)/-5=y

So the inverse function is f'(x)=-(x+42)/5 (note that f' means inverse)