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Let f(x)=x^(2)-4x-3, x gt2 and g(x) be t...

Let `f(x)=x^(2)-4x-3, x gt2` and `g(x)` be the inverse of `f(x)`. Then the value `fo(g')`, where `f(x)=2`, is `"(here, g' represents the first derivative of g)"`

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To solve the problem, we need to find the value of \( g'(5) \) where \( g(x) \) is the inverse function of \( f(x) = x^2 - 4x - 3 \) for \( x > 2 \), and we know that \( f(g(x)) = x \). ### Step-by-Step Solution: 1. **Identify the function**: \[ f(x) = x^2 - 4x - 3 \] 2. **Find \( f(x) = 2 \)**: We need to solve the equation: \[ x^2 - 4x - 3 = 2 \] Rearranging gives: \[ x^2 - 4x - 5 = 0 \] 3. **Factor the quadratic**: The equation can be factored as: \[ (x - 5)(x + 1) = 0 \] Thus, the solutions are: \[ x = 5 \quad \text{or} \quad x = -1 \] 4. **Select the valid solution**: Since \( x > 2 \), we take: \[ x = 5 \] Therefore, \( g(2) = 5 \). 5. **Differentiate the relationship**: From the relationship \( g(f(x)) = x \), we differentiate both sides with respect to \( x \): \[ g'(f(x)) \cdot f'(x) = 1 \] 6. **Find \( f'(x) \)**: Differentiate \( f(x) \): \[ f'(x) = 2x - 4 \] 7. **Evaluate \( f'(5) \)**: Substitute \( x = 5 \) into \( f'(x) \): \[ f'(5) = 2(5) - 4 = 10 - 4 = 6 \] 8. **Use the derivative relationship**: Substitute \( x = 5 \) into the differentiated equation: \[ g'(f(5)) \cdot f'(5) = 1 \] Since \( f(5) = 2 \): \[ g'(2) \cdot 6 = 1 \] 9. **Solve for \( g'(2) \)**: \[ g'(2) = \frac{1}{6} \] ### Final Answer: Thus, the value of \( g'(2) \) is: \[ \boxed{\frac{1}{6}} \]
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