if f(x)=x^2 -1. what is the equation for f^-1(x)
....f^-1(x)= +/- (squareroot all)x+1
...f^-1(x)= +/- (squareroot all )x-1
....f^-1(x)= +/- (squareroot x only) x+1
....f^-1(x)= +/- (squareroot x only) x-1

Question

if f(x)=x^2 -1. what is the equation for f^-1(x)
....f^-1(x)= +/- (squareroot all)x+1
...f^-1(x)= +/- (squareroot all )x-1
....f^-1(x)= +/- (squareroot x only) x+1 
....f^-1(x)= +/- (squareroot x only) x-1

anonymous · Answer

$$y=x^2-1$$
switch x and y
$$x=y^2-1$$
solve for y
$$x+1=y^2$$
$$y=\pm\sqrt{x+1}$$

anonymous · Answer

but this is not a function, so cannot be one of the answers.  did they restrict the domain of f?

anonymous · Answer

nope

anonymous · Answer

then there is a mistake here some place.

you cannot write $$f^{-1}(x)=\pm\sqrt{x+1}$$ because a function cannot have two answers.  on the other hand you are not allowed just to pick one