If [tex][tex]$f(x)=5x$[/tex][/tex], what is [tex][tex]$f^{-1}(x)$[/tex][/tex]?

A. [tex][tex]$f^{-1}(x)=-5x$[/tex][/tex]
B. [tex][tex]$f^{-1}(x)=-\frac{1}{5}x$[/tex][/tex]
C. [tex][tex]$f^{-1}(x)=\frac{1}{5}x$[/tex][/tex]
D. [tex][tex]$f^{-1}(x)=5x$[/tex][/tex]



Answer :

To find the inverse function of [tex]\( f(x) = 5x \)[/tex], denoted as [tex]\( f^{-1}(x) \)[/tex], follow these steps:

1. Express the Function:
Start with the function given:
[tex]\[ f(x) = 5x \][/tex]

2. Replace [tex]\( f(x) \)[/tex] with [tex]\( y \)[/tex]:
For clarity, let's rewrite the function as:
[tex]\[ y = 5x \][/tex]

3. Solve for [tex]\( x \)[/tex] in terms of [tex]\( y \)[/tex]:
We need to express [tex]\( x \)[/tex] in terms of [tex]\( y \)[/tex]. To do this, we solve the equation for [tex]\( x \)[/tex]:
[tex]\[ y = 5x \][/tex]

Divide both sides by 5 to isolate [tex]\( x \)[/tex]:
[tex]\[ x = \frac{y}{5} \][/tex]

4. Write the Inverse Function:
Since [tex]\( x \)[/tex] is expressed in terms of [tex]\( y \)[/tex], we can now write the inverse function by replacing [tex]\( y \)[/tex] with [tex]\( x \)[/tex]:
[tex]\[ f^{-1}(x) = \frac{x}{5} \][/tex]

This can also be written as:
[tex]\[ f^{-1}(x) = \frac{1}{5}x \][/tex]

So, the inverse function of [tex]\( f(x) = 5x \)[/tex] is [tex]\( f^{-1}(x) = \frac{1}{5}x \)[/tex].

Therefore, the correct answer is:
[tex]\[ f^{-1}(x) = \frac{1}{5} x \][/tex]