Solve for x please help (show ur work)

Which of the following system of equation is not equal to the system of equations is not equal to the system of equations shown below

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

5× 1/2 = ? a) more than 5 because you are multiplying by a whole number b) 5/10 because you multiply the numerator and denominator by 5 c) less than 5 because you are multiplying by a number that is more than 1 d) less than 5 because you are multiplying by a number that is less than 1