Question

Let f(x)=2x−3f(x)=2x−3.  Determine the input for x when f(x)=9.f(x)=9.

Answer 1

The given function is

`f(x)=2x-3`

The expression f(x)=9 means that we have to replace it for 9 and solve for x.

`9=2x-3`

We add 3 on each side.

`\begin{gathered} 9+3=2x-3+3 \\ 12=2x \end{gathered}`

Then, we divide the equation by 2.

`\begin{gathered} (2x)/(2)=(12)/(2) \\ x=6 \end{gathered}`

Therefore, when f(x) = 9, x = 6.