Answer
f and g are inverses
Work Step by Step
g(f(x)) = g($x^{2}$ - 9) = $\sqrt {x^{2} - 9 + 9}$ =$ \sqrt {x^{2}}$ = x
f(g(x)) = $f(\sqrt {x + 9})$ = ${(\sqrt {x + 9})^{2}}$ - 9 = x + 9 - 9 = x
Since g(f(x)) = f(g(x)) are equal to each other, f and g are inverses
