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STATEMENT -1 : f(x)= (1 -cos(1-cosx))/x...

STATEMENT -1 : `f(x)= (1 -cos(1-cosx))/x^(4)` is continuous if f(0)=1/8
and
STATEMENT -2 : ` lim_( x to 0^(+)) f(x) = lim_(x to 0^(-)) f(x) = 1/8`

A

Statement -1 is True, Statement -2 is True, Statement -2 is a correct explantion for Statement -1

B

Statement -1 is True, Statement -2 is True, Statement -2 is NOT a correct explanation for Statement -1

C

Statement -1 is True , Statement -2 is Flase

D

Statement -1 is Flase , Statement - 2 is True

Text Solution

AI Generated Solution

The correct Answer is:
To determine the continuity of the function \( f(x) = \frac{1 - \cos(1 - \cos x)}{x^4} \) at \( x = 0 \) and to evaluate the limits as \( x \) approaches 0 from both sides, we will follow these steps: ### Step 1: Evaluate \( f(0) \) We need to define \( f(0) \) to check continuity. The statement claims that \( f(0) = \frac{1}{8} \). ### Step 2: Find the limit as \( x \) approaches 0 We need to compute: \[ \lim_{x \to 0} f(x) = \lim_{x \to 0} \frac{1 - \cos(1 - \cos x)}{x^4} \] ### Step 3: Analyze the limit As \( x \to 0 \): - \( \cos x \to 1 \) - Therefore, \( 1 - \cos x \to 0 \) - Consequently, \( 1 - \cos(1 - \cos x) \to 1 - \cos(0) = 0 \) Both the numerator and denominator approach 0, which indicates we can apply L'Hôpital's Rule or use Taylor series expansion. ### Step 4: Use Taylor series expansion Using the Taylor series expansion for \( \cos x \): \[ \cos x \approx 1 - \frac{x^2}{2} + O(x^4) \] Thus, \[ 1 - \cos x \approx \frac{x^2}{2} \] Substituting this into \( f(x) \): \[ 1 - \cos(1 - \cos x) \approx 1 - \cos\left(\frac{x^2}{2}\right) \] Using the Taylor expansion for \( \cos \): \[ \cos\left(\frac{x^2}{2}\right) \approx 1 - \frac{(x^2/2)^2}{2} = 1 - \frac{x^4}{8} \] So, \[ 1 - \cos\left(\frac{x^2}{2}\right) \approx \frac{x^4}{8} \] ### Step 5: Substitute back into the limit Now substituting back into the limit: \[ f(x) \approx \frac{\frac{x^4}{8}}{x^4} = \frac{1}{8} \] Thus, \[ \lim_{x \to 0} f(x) = \frac{1}{8} \] ### Step 6: Check continuity Since: \[ \lim_{x \to 0} f(x) = \frac{1}{8} = f(0) \] we conclude that \( f(x) \) is continuous at \( x = 0 \). ### Conclusion Both statements are correct: - **Statement 1**: \( f(x) \) is continuous at \( x = 0 \) if \( f(0) = \frac{1}{8} \). - **Statement 2**: \( \lim_{x \to 0^{+}} f(x) = \lim_{x \to 0^{-}} f(x) = \frac{1}{8} \).
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