Horizontal Stretches of Functions

Question

If $y = f(x)$, then $y' = f(kx)$ is a horizontal stretch of the function when $k \neq 1$ and $k < 0$.

In the above image, why is my answer incorrect?

Answer 1

For $1/3 x$ you would have the minimum on the same side of the $y$ axis. The $-$ sign means that it is a reflection with respect to the vertical axis through the origin.

Answer 2

Assuming each grid square is $1\times 1$, we have, for example, $f(2)=4$ and $g(-6)=4$. So we have $f(2)=f\left(-\frac{1}{3}(-6)\right)=g(-6)$.