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Find the inverse of the function.

15. [tex]\( f(x) = -2x + 11 \)[/tex]

16. [tex]\( g(x) = \frac{4}{x + 7} \)[/tex]


Sagot :

Sure! Let's find the inverse of each function step by step.

### Finding the inverse of [tex]\( f(x) = -2x + 11 \)[/tex]

1. Start with the function:
[tex]\[ f(x) = -2x + 11 \][/tex]

2. To find the inverse, we first replace [tex]\( f(x) \)[/tex] with [tex]\( y \)[/tex]:
[tex]\[ y = -2x + 11 \][/tex]

3. Next, interchange [tex]\( x \)[/tex] and [tex]\( y \)[/tex]:
[tex]\[ x = -2y + 11 \][/tex]

4. Solve this equation for [tex]\( y \)[/tex]:
[tex]\[ x = -2y + 11 \][/tex]
[tex]\[ x - 11 = -2y \][/tex]
[tex]\[ -2y = x - 11 \][/tex]
[tex]\[ y = \frac{11 - x}{2} \][/tex]

5. Replace [tex]\( y \)[/tex] with [tex]\( f^{-1}(x) \)[/tex]:
[tex]\[ f^{-1}(x) = \frac{11 - x}{2} \][/tex]

So, the inverse function of [tex]\( f(x) = -2x + 11 \)[/tex] is:
[tex]\[ f^{-1}(x) = \frac{11 - x}{2} \][/tex]

### Finding the inverse of [tex]\( g(x) = \frac{4}{x + 7} \)[/tex]

1. Start with the function:
[tex]\[ g(x) = \frac{4}{x + 7} \][/tex]

2. To find the inverse, replace [tex]\( g(x) \)[/tex] with [tex]\( y \)[/tex]:
[tex]\[ y = \frac{4}{x + 7} \][/tex]

3. Interchange [tex]\( x \)[/tex] and [tex]\( y \)[/tex]:
[tex]\[ x = \frac{4}{y + 7} \][/tex]

4. Solve this equation for [tex]\( y \)[/tex]:
[tex]\[ x(y + 7) = 4 \][/tex]
[tex]\[ xy + 7x = 4 \][/tex]
[tex]\[ xy = 4 - 7x \][/tex]
[tex]\[ y = \frac{4 - 7x}{x} \][/tex]

5. Replace [tex]\( y \)[/tex] with [tex]\( g^{-1}(x) \)[/tex]:
[tex]\[ g^{-1}(x) = \frac{4 - 7x}{x} \][/tex]

So, the inverse function of [tex]\( g(x) = \frac{4}{x + 7} \)[/tex] is:
[tex]\[ g^{-1}(x) = \frac{4 - 7x}{x} \][/tex]

In summary:
1. The inverse of [tex]\( f(x) = -2x + 11 \)[/tex] is [tex]\( f^{-1}(x) = \frac{11 - x}{2} \)[/tex].
2. The inverse of [tex]\( g(x) = \frac{4}{x + 7} \)[/tex] is [tex]\( g^{-1}(x) = \frac{4 - 7x}{x} \)[/tex].