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If f(x) = {{:(|1-4x^(2)|",",0 le x lt 1)...

If `f(x) = {{:(|1-4x^(2)|",",0 le x lt 1),([x^(2)-2x]",",1 le x lt 2):}`, where [] denotes the greatest integer function, then

A. f(x) is continuous for all `x in [0, 2)`
B. f(x) is differentiable for all `x in [0, 2) - {1}`
C. f(X) is differentiable for all `x in [0, 2)-{(1)/(2),1}`
D. None of these

A

f(x) is continuous for all `x in [0, 2)`

B

f(x) is differentiable for all `x in [0, 2) - {1}`

C

f(X) is differentiable for all `x in [0, 2)-{(1)/(2),1}`

D

None of these

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze the function \( f(x) \) defined in two parts: 1. For \( 0 \leq x < 1 \): \( f(x) = |1 - 4x^2| \) 2. For \( 1 \leq x < 2 \): \( f(x) = [x^2 - 2x] \) where \( [ ] \) denotes the greatest integer function. ### Step 1: Check Continuity at \( x = 1 \) To check if \( f(x) \) is continuous at \( x = 1 \), we need to evaluate the left-hand limit, right-hand limit, and the function value at that point. - **Left-hand limit as \( x \to 1^- \)**: \[ f(1^-) = |1 - 4(1)^2| = |1 - 4| = | -3 | = 3 \] - **Right-hand limit as \( x \to 1^+ \)**: \[ f(1^+) = [1^2 - 2(1)] = [1 - 2] = [-1] = -1 \] - **Function value at \( x = 1 \)**: \[ f(1) = [1^2 - 2(1)] = [1 - 2] = [-1] = -1 \] Since \( f(1^-) = 3 \) and \( f(1^+) = -1 \), we see that: \[ f(1^-) \neq f(1^+) \] Thus, \( f(x) \) is not continuous at \( x = 1 \). ### Step 2: Check Differentiability in the intervals #### For \( 0 \leq x < 1 \): The function \( f(x) = |1 - 4x^2| \) is differentiable except where the expression inside the absolute value is zero. - Set \( 1 - 4x^2 = 0 \): \[ 4x^2 = 1 \implies x^2 = \frac{1}{4} \implies x = \frac{1}{2} \] Thus, \( f(x) \) is not differentiable at \( x = \frac{1}{2} \). #### For \( 1 \leq x < 2 \): The function \( f(x) = [x^2 - 2x] \) is a piecewise constant function, and it is differentiable everywhere except at points where the greatest integer function changes value. - Calculate \( x^2 - 2x \) at the endpoints: - At \( x = 1 \): \( f(1) = -1 \) - At \( x = 2 \): \( f(2) = 0 \) The function \( x^2 - 2x \) is continuous and differentiable in the interval \( [1, 2) \) but not at \( x = 1 \) because of the transition from the first piece to the second piece. ### Conclusion: - \( f(x) \) is not continuous at \( x = 1 \). - \( f(x) \) is not differentiable at \( x = \frac{1}{2} \) and also at \( x = 1 \). ### Final Answer: - A. False: \( f(x) \) is not continuous for all \( x \in [0, 2) \). - B. False: \( f(x) \) is not differentiable at \( x = 1 \). - C. True: \( f(x) \) is not differentiable at \( x = \frac{1}{2} \) and \( x = 1 \). - D. False: One of the options is correct. Thus, the correct option is **C**.
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