functions- higher maths

Question

f(x)= 1/X²-1 g(x) = 3x-1

do G(F(X))

can anyone explain how the Answer is 4-x²/x²-1

Answer 1

f(x) = 1/(x²-1)  g(x) = 3x-1

 

g(f(x) = g(1/(x²-1)) = 3(1/(x²-1))  - 1

 

                              = [3 - (x²-1)] / (x²-1) = (4-x²) / (x²-1)