Below is a portion of the graph of an invertible function f(x)
What is $f^{-1}(1) + f^{-1}(2) + f^{-1}(4)$?
We have the points on the original graph (-1,1) ( 0,2) and (2,4)
The inverse reverses the coordinates ( 1, -1) ( 2,0) and ( 4,2)
So
f -1 (1) + f -1 (2) + f -1(4) = -1 + 0 + 2 = 1
