To find the inverse we have to first change the function notation to 'y'
So
f(x) = -x becomes y = -x
Next, we have to switch the x and y values
So, y = -x becomes x = -y
Now, we have to solve for y.
y = -x
So the inverse of f(x) = -x is:
[tex]f^{-1}(x) = -x[/tex]