Question

For which pair of functions is (g o f)(a)= lal-2

Answer 1

One convenient choice is
- f(a) = |a|
- g(x) = x − 2.

Then (g ∘ f)(a) = g(f(a)) = g(|a|) = |a| − 2.

(Equivalently you could take f(a)=a and g(x)=|x|−2; both give (g∘f)(a)=|a|−2.)