Let f(x)=x^2 -81. Find f^1(x)
Hello,I suppose you mean -1! else f(x)=f^1(x)y=x²-81-> x=y²-81 (exchahge x and y)->y²=x+81 (solve for y)\(y= \sqrt{x+81} \ or \ y=- \sqrt{x+81}\) It is because (f^-1)(x) is not a function! with x>=-81
