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f(x) =(x-1)^(1/(2-x)) is not defined at...

`f(x) =(x-1)^(1/(2-x))` is not defined at x = 2. If f(x) is continuous, then f(2) is equal to:

A

e

B

`e^(-1)`

C

`e^(-2)`

D

1

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the value of \( f(2) \) such that the function \( f(x) = (x - 1)^{\frac{1}{2 - x}} \) is continuous at \( x = 2 \). ### Step-by-Step Solution 1. **Understanding Continuity**: For \( f(x) \) to be continuous at \( x = 2 \), we need: \[ f(2) = \lim_{x \to 2} f(x) \] 2. **Finding the Limit**: We need to evaluate: \[ \lim_{x \to 2} (x - 1)^{\frac{1}{2 - x}} \] As \( x \) approaches 2, \( (x - 1) \) approaches \( 1 \) and \( (2 - x) \) approaches \( 0 \). This results in the expression taking the form \( 1^{\infty} \), which is indeterminate. 3. **Using the Exponential Form**: We can rewrite the expression using the exponential function: \[ (x - 1)^{\frac{1}{2 - x}} = e^{\frac{\ln(x - 1)}{2 - x}} \] Therefore, we need to evaluate: \[ \lim_{x \to 2} e^{\frac{\ln(x - 1)}{2 - x}} \] 4. **Finding the Limit of the Exponent**: We focus on: \[ \lim_{x \to 2} \frac{\ln(x - 1)}{2 - x} \] As \( x \to 2 \), \( \ln(x - 1) \) approaches \( \ln(1) = 0 \) and \( (2 - x) \) approaches \( 0 \), leading to the indeterminate form \( \frac{0}{0} \). We can apply L'Hôpital's Rule. 5. **Applying L'Hôpital's Rule**: Differentiate the numerator and the denominator: - Derivative of \( \ln(x - 1) \) is \( \frac{1}{x - 1} \) - Derivative of \( 2 - x \) is \( -1 \) Thus, we have: \[ \lim_{x \to 2} \frac{\ln(x - 1)}{2 - x} = \lim_{x \to 2} \frac{\frac{1}{x - 1}}{-1} = -\lim_{x \to 2} \frac{1}{x - 1} \] As \( x \to 2 \), \( x - 1 \to 1 \), so: \[ -\frac{1}{1} = -1 \] 6. **Final Limit Calculation**: Now substituting back, we get: \[ \lim_{x \to 2} e^{\frac{\ln(x - 1)}{2 - x}} = e^{-1} \] 7. **Conclusion**: Therefore, since \( f(2) = \lim_{x \to 2} f(x) \): \[ f(2) = e^{-1} \] ### Final Answer: \[ f(2) = \frac{1}{e} \]
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