Question

If f(x) = 5x – 3, then what is f–1(x) ?

Answer 1

(x+3)/5

Answer 2

f(-1)?

Answer 3

or f(-x)?

Answer 4

You mean the inverse of f(x). Just swap your x and y variables and solve for y.

Answer 5

@billybob3 did you understand how to get this?

Answer 6

i think he's just waiting for the answer :(

Answer 7

yeah, you switch x and y

Answer 8

Yes, so what's the problem?

Answer 9

@billybob3
Inverse of a function is defined such that
\[f^{-1} (f(x))=f(f^{-1}(x))=x\]
We'll use this to find \(f^{-1} (x)\)
We have
\[f(x)=5x-3\]
to find \(f^{-1} (x)\) put x= \(f^{-1} (x)\), we have
\[f(f^{-1}(x))= 5 f^{-1} (x)-3\]
we get
\[x= 5 f^{-1} (x)-3\]
\[5 f^{-1} (x)= x+3\]
or
\[f^{-1} (x)=\frac{x+3}{5}\]