Question: what is the inverse function of x^2-7?
Answer: Since g(f(x))=x g ( f ( x ) ) = x , f−1(x)=√x+7,−√x+7 f - 1 ( x ) = x + 7 , - x + 7 is the inverse of f(x)=x2−7 f ( x ) = x 2 - 7 .