In order to vertically stretch a function by a factor k, we have to multiply the function expression by k.
So, in order to stretch the function by a factor of 1/5, we simply have to multiply:
[tex]f(x) = -5x \implies g(x) = -5x\cdot\dfrac{1}{5}=-x[/tex]
So, if we shrink the function -5x by a factor of 1/5, we get the function -x.
