Verify that f and g are inverse functions algebraically and graphically. f(x) = X+8 X-7' g(x) = 7x + 8 X-1

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Author:Erwin Kreyszig
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## Verification of Inverse Functions

### Verify algebraically and graphically that \( f \) and \( g \) are inverse functions.

Given:
\[ f(x) = \frac{x + 8}{x - 7} \]
\[ g(x) = \frac{7x + 8}{x - 1} \]

### (a) Algebraically

#### Step 1: Check if \( f(g(x)) = x \)

\[ f(g(x)) = f \left( \frac{7x + 8}{x - 1} \right) \]

Substitute \( g(x) \) into \( f(x) \):

\[ = \frac{\frac{7x + 8}{x - 1} + 8}{\frac{7x + 8}{x - 1} - 7} \]

Simplify the expression step-by-step:

\[ = \frac{\frac{7x + 8 + 8(x - 1)}{x - 1}}{\frac{7x + 8 - 7(x - 1)}{x - 1}} \]

\[ = \frac{7x + 8 + 8x - 8}{7x + 8 - 7x + 7} \]

\[ = \frac{15x}{15} = x \]

Thus, \( f(g(x)) = x \).

#### Step 2: Check if \( g(f(x)) = x \)

\[ g(f(x)) = g \left( \frac{x + 8}{x - 7} \right) \]

Substitute \( f(x) \) into \( g(x) \):

\[ = \frac{7 \left( \frac{x + 8}{x - 7} \right) + 8}{\frac{x + 8}{x - 7} - 1} \]

Simplify the expression step-by-step:

\[ = \frac{\frac{7(x + 8)}{x - 7} + 8}{\frac{x + 8}{x - 7} - \frac{x - 7}{x - 7}} \]

\[ = \frac{\frac{7x + 56 + 8(x - 7)}{x - 7}}{\frac{x + 8 - (x - 7)}{x -
Transcribed Image Text:## Verification of Inverse Functions ### Verify algebraically and graphically that \( f \) and \( g \) are inverse functions. Given: \[ f(x) = \frac{x + 8}{x - 7} \] \[ g(x) = \frac{7x + 8}{x - 1} \] ### (a) Algebraically #### Step 1: Check if \( f(g(x)) = x \) \[ f(g(x)) = f \left( \frac{7x + 8}{x - 1} \right) \] Substitute \( g(x) \) into \( f(x) \): \[ = \frac{\frac{7x + 8}{x - 1} + 8}{\frac{7x + 8}{x - 1} - 7} \] Simplify the expression step-by-step: \[ = \frac{\frac{7x + 8 + 8(x - 1)}{x - 1}}{\frac{7x + 8 - 7(x - 1)}{x - 1}} \] \[ = \frac{7x + 8 + 8x - 8}{7x + 8 - 7x + 7} \] \[ = \frac{15x}{15} = x \] Thus, \( f(g(x)) = x \). #### Step 2: Check if \( g(f(x)) = x \) \[ g(f(x)) = g \left( \frac{x + 8}{x - 7} \right) \] Substitute \( f(x) \) into \( g(x) \): \[ = \frac{7 \left( \frac{x + 8}{x - 7} \right) + 8}{\frac{x + 8}{x - 7} - 1} \] Simplify the expression step-by-step: \[ = \frac{\frac{7(x + 8)}{x - 7} + 8}{\frac{x + 8}{x - 7} - \frac{x - 7}{x - 7}} \] \[ = \frac{\frac{7x + 56 + 8(x - 7)}{x - 7}}{\frac{x + 8 - (x - 7)}{x -
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