Given: f(x)=2x+7 and g(x)=x-5.
What is the value of (g^-1 X f^-1)(9)?
Well, g^-1(x) = f(x) and f^-1(x) = g(x)
Therefore, (g^-1 X f^-1)(9) = (f X g)(9) = f(9) X g(9)
f(x) = 2x + 7 , therefore f(9) = 2x9 + 7 = 18 + 7 = 25
g(x) = x – 5, therefore g(9) = 9 – 5 = 4
Giving, f(9) X g(9) = 25 X 4 = 100
Answer: 100