Question

The function f(x) = -3x - 4 was replaced with f(x + k) resulting in the function g(x) = -3x - 13. What is the value of k? A. -9 B. -3 C. 3 D. 9

Answer 1

$f(x+k)=-3(x+k)-4$$-3x-13=-3x-3k-4$

then we need to solve the second equation for k

$3k=-4+13=9$

then the answer is C.

$k=3$