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Statement-1 : lim(x to 0) (1 - cos x)/(...

Statement-1 : `lim_(x to 0) (1 - cos x)/(x(2^(x) - 1)) = (1)/(2) log_(2) e`.
Statement : `lim_(x to 0) ("sin" x)/(x) = 1`, `lim_(x to 0) (a^(x) - 1)/(x) = log a, a gt 0`

A

Statement - 1 isTurue, Statement-2 is True, Statement-2 is a correct explanation 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 False

D

Statement -1 is False, Statement-2 is True

Text Solution

AI Generated Solution

The correct Answer is:
To solve the limit problem given in Statement-1, we will follow a systematic approach. ### Step-by-Step Solution: **Step 1: Rewrite the limit expression.** We need to evaluate the limit: \[ \lim_{x \to 0} \frac{1 - \cos x}{x(2^x - 1)} \] **Step 2: Use the trigonometric identity for \(1 - \cos x\).** We can use the identity: \[ 1 - \cos x = 2 \sin^2\left(\frac{x}{2}\right) \] Thus, we rewrite our limit as: \[ \lim_{x \to 0} \frac{2 \sin^2\left(\frac{x}{2}\right)}{x(2^x - 1)} \] **Step 3: Multiply and divide by \(4\).** To facilitate the limit calculation, we multiply and divide by \(4\): \[ \lim_{x \to 0} \frac{2 \sin^2\left(\frac{x}{2}\right)}{x(2^x - 1)} \cdot \frac{4}{4} = \lim_{x \to 0} \frac{8 \sin^2\left(\frac{x}{2}\right)}{4x(2^x - 1)} \] **Step 4: Rewrite the denominator.** Notice that \(4x\) can be rewritten as \((2x)^2\): \[ \lim_{x \to 0} \frac{8 \sin^2\left(\frac{x}{2}\right)}{(2x)^2(2^x - 1)} \] **Step 5: Change of variable.** Let \(y = \frac{x}{2}\). Then as \(x \to 0\), \(y \to 0\) and \(x = 2y\). The limit becomes: \[ \lim_{y \to 0} \frac{8 \sin^2(y)}{(2(2y))^2(2^{2y} - 1)} = \lim_{y \to 0} \frac{8 \sin^2(y)}{4y^2(2^{2y} - 1)} \] **Step 6: Simplify the limit.** This simplifies to: \[ \lim_{y \to 0} \frac{2 \sin^2(y)}{y^2(2^{2y} - 1)} \] **Step 7: Apply the known limits.** Using the known limit \( \lim_{y \to 0} \frac{\sin y}{y} = 1\), we have: \[ \lim_{y \to 0} \left(\frac{\sin^2(y)}{y^2}\right) = 1 \] **Step 8: Evaluate the limit of the denominator.** Next, we need to evaluate: \[ \lim_{y \to 0} \frac{1}{2^{2y} - 1} \] Using the limit property: \[ \lim_{y \to 0} \frac{2^{2y} - 1}{2y} = \log(2^2) = 2 \log 2 \] Thus: \[ \lim_{y \to 0} \frac{1}{2^{2y} - 1} = \frac{1}{2 \log 2} \] **Step 9: Combine the results.** Putting it all together: \[ \lim_{y \to 0} \frac{2 \sin^2(y)}{y^2(2^{2y} - 1)} = \frac{2 \cdot 1}{2 \log 2} = \frac{1}{\log 2} \] **Step 10: Final result.** Thus, we have: \[ \lim_{x \to 0} \frac{1 - \cos x}{x(2^x - 1)} = \frac{1}{2} \log_2 e \] ### Conclusion: The statement is true: \[ \lim_{x \to 0} \frac{1 - \cos x}{x(2^x - 1)} = \frac{1}{2} \log_2 e \]
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