Question

Let f(x) = 2x − 6. Solve f^−1(x) when x = 2.

I think it is 4.

f(x) = 2x - 6
y = 2x - 6
x = 2y - 6
+6 + 6
x + 6 = 2y
----- ----
2 2
x + 6
----- = y or f^-1(x)
2

x = 2:

2 + 6 8
----- = ---
2 2
8
--- = 4
2

Answer 1

well, does f(4) = 2?

yes.

and, your solution of (x+6)/2 is correct