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Which function is the inverse of the function [tex]f(x)=\frac{x+2}{7}[/tex]?

A. [tex]q(x)=\frac{-x+2}{7}[/tex]

B. [tex]r(x)=\frac{7}{x+2}[/tex]

C. [tex]p(x)=7x-2[/tex]

D. [tex]s(x)=2x+7[/tex]


Sagot :

To find the inverse of the function [tex]\( f(x) = \frac{x + 2}{7} \)[/tex], we need to follow these steps:

1. Express [tex]\( y \)[/tex] in terms of [tex]\( x \)[/tex]:
[tex]\[ y = \frac{x + 2}{7} \][/tex]

2. Swap [tex]\( x \)[/tex] and [tex]\( y \)[/tex]:
This means replacing all instances of [tex]\( y \)[/tex] by [tex]\( x \)[/tex], and all instances of [tex]\( x \)[/tex] by [tex]\( y \)[/tex]:
[tex]\[ x = \frac{y + 2}{7} \][/tex]

3. Solve for [tex]\( y \)[/tex]:
To isolate [tex]\( y \)[/tex], start by multiplying both sides of the equation by 7:
[tex]\[ 7x = y + 2 \][/tex]
Then, subtract 2 from both sides:
[tex]\[ y = 7x - 2 \][/tex]

So the inverse function is [tex]\( f^{-1}(x) = 7x - 2 \)[/tex].

From the given options:
- Option A: [tex]\(\frac{-x + 2}{7}\)[/tex] is not the correct inverse.
- Option B: [tex]\(\frac{7}{x + 2}\)[/tex] is not the correct inverse.
- Option C: [tex]\(7x - 2\)[/tex] corresponds to the correct inverse function we found.
- Option D: [tex]\(2x + 7\)[/tex] is not the correct inverse.

Thus, the correct answer is:
[tex]\[ \boxed{C} \][/tex]