Question

If f(x) = 2x+1/x-4, what is the value of f -1(3)?

Answer 1

\[f^{-1}\]

Answer 2

you can do a trick.
plug in 3 instead of f(x)
and solve for x, but denote your x as \({\rm f}^{-1}(x)\)

Answer 3

\[f^{-1}(3)=a \text{ means } f(a)=3 \text{ if } f \text{ is invertible of course }\]
so you could just solve
\[\frac{2a+1}{a-4}=3 \text{ for } a \]

Answer 4

13

Answer 5

thank you both

Answer 6

13?

Answer 7

you solved that so quickly
good job

Answer 8

13

Answer 9

yeah, 13.... machine!

Answer 10

cool