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Let f(x)=8x^(3)-6x^(2)-2x+1, then...

Let `f(x)=8x^(3)-6x^(2)-2x+1,` then

A

`f(x)=0` has no root in (0, 1)

B

`f(x)=0` has atleast one root in (0, 1)

C

f'(c) vanishes for some `c in (0, 1)`

D

None of tha above

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to analyze the function \( f(x) = 8x^3 - 6x^2 - 2x + 1 \) and determine the behavior of this function in the interval \( [0, 1] \). ### Step-by-Step Solution: 1. **Evaluate \( f(0) \)**: \[ f(0) = 8(0)^3 - 6(0)^2 - 2(0) + 1 = 1 \] 2. **Evaluate \( f(1) \)**: \[ f(1) = 8(1)^3 - 6(1)^2 - 2(1) + 1 = 8 - 6 - 2 + 1 = 1 \] 3. **Compare \( f(0) \) and \( f(1) \)**: \[ f(0) = 1 \quad \text{and} \quad f(1) = 1 \] Since \( f(0) = f(1) \), we can apply Rolle's Theorem. 4. **Apply Rolle's Theorem**: - According to Rolle's Theorem, if \( f(a) = f(b) \) for some interval \( [a, b] \), then there exists at least one \( c \) in \( (a, b) \) such that \( f'(c) = 0 \). 5. **Conclusion**: - Since \( f(0) = f(1) \), there exists at least one \( c \) in the interval \( (0, 1) \) such that \( f'(c) = 0 \). ### Final Answer: The correct option is that \( f'(c) \) vanishes for some \( c \) belonging to \( (0, 1) \).
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