PLEASE HELPPP ?!?!?

Can someone with this? ! the answer choices are 1, 1.3, 1.45, and 1.9!

Show algebraically that f and g are inverse functions f(x)=x^2/-6; g(x)=square root of 2x+12

The physical fitness of an athlete is often measured by how much oxygen the athlete takes in (which is recorded in milliliters per kilogram, ml/kg). the mean maximum oxygen uptake for elite athletes has been found to be 60 with a standard deviation of 7.2. assume that the distribution is approximately normal.