Construct a circle through points X, Y, and Z

For the equation below, x is the input and y is the output. y = -4x + 3 if the input is -8, then the output is

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

Change negative exponents to positive. then solve. round to four decimal places