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lim(x to 0) (A "sin" x + B log (1 + x^(...

`lim_(x to 0) (A "sin" x + B log (1 + x^(2)) + C (1 - cos x))/(x^(2)) = 2` then
Statement-1 : A = 1
Statement-2 : 2B + C = 4
Statement-3 A + B + C = 0

A

TTT

B

TTF

C

FTF

D

FFF

Text Solution

AI Generated Solution

The correct Answer is:
To solve the limit problem, we need to evaluate the limit: \[ \lim_{x \to 0} \frac{A \sin x + B \log(1 + x^2) + C(1 - \cos x)}{x^2} = 2 \] ### Step 1: Expand the terms in the limit 1. **Expand \(\sin x\)** using its Taylor series: \[ \sin x = x - \frac{x^3}{6} + O(x^5) \] 2. **Expand \(\log(1 + x^2)\)** using its Taylor series: \[ \log(1 + x^2) = x^2 - \frac{x^4}{2} + O(x^6) \] 3. **Expand \(1 - \cos x\)** using its Taylor series: \[ 1 - \cos x = \frac{x^2}{2} - \frac{x^4}{24} + O(x^6) \] ### Step 2: Substitute the expansions into the limit Substituting these expansions into the limit, we get: \[ \lim_{x \to 0} \frac{A\left(x - \frac{x^3}{6} + O(x^5)\right) + B\left(x^2 - \frac{x^4}{2} + O(x^6)\right) + C\left(\frac{x^2}{2} - \frac{x^4}{24} + O(x^6)\right)}{x^2} \] ### Step 3: Simplify the expression This simplifies to: \[ \lim_{x \to 0} \frac{Ax - \frac{Ax^3}{6} + Bx^2 - \frac{Bx^4}{2} + \frac{Cx^2}{2} - \frac{Cx^4}{24}}{x^2} \] Breaking this down, we can separate the terms: \[ = \lim_{x \to 0} \left( \frac{A}{x} - \frac{A}{6}x + B + \frac{C}{2} - \frac{B}{2}x^2 - \frac{C}{24}x^2 \right) \] ### Step 4: Evaluate the limit as \(x \to 0\) As \(x \to 0\), the term \(\frac{A}{x}\) will diverge unless \(A = 0\). Therefore, we set \(A = 0\). Now our limit simplifies to: \[ \lim_{x \to 0} \left( B + \frac{C}{2} \right) = 2 \] This gives us the equation: \[ B + \frac{C}{2} = 2 \quad \text{(1)} \] ### Step 5: Analyze the second term From the expansion of \(\log(1 + x^2)\): \[ \lim_{x \to 0} \frac{B \log(1 + x^2)}{x^2} = B \] And for \(1 - \cos x\): \[ \lim_{x \to 0} \frac{C(1 - \cos x)}{x^2} = \frac{C}{2} \] Thus, we have: \[ B + \frac{C}{2} = 2 \] ### Step 6: Analyze the third term From the expansion of \(1 - \cos x\): \[ \lim_{x \to 0} \frac{C(1 - \cos x)}{x^2} = \frac{C}{2} \] ### Step 7: Solve for \(C\) From the limit, we also have: \[ 2B + C = 4 \quad \text{(2)} \] ### Step 8: Solve the equations Now we have two equations: 1. \(B + \frac{C}{2} = 2\) 2. \(2B + C = 4\) From equation (1), we can express \(C\) in terms of \(B\): \[ C = 4 - 2B \] Substituting this into equation (1): \[ B + \frac{4 - 2B}{2} = 2 \] \[ B + 2 - B = 2 \quad \Rightarrow \quad 2 = 2 \] This is always true, so we need another condition. ### Step 9: Find \(A + B + C = 0\) Since \(A = 0\), we can conclude: \[ 0 + B + C = 0 \quad \Rightarrow \quad B + C = 0 \quad \text{(3)} \] ### Step 10: Solve for \(B\) and \(C\) From equation (2): \[ C = 4 - 2B \] Substituting into equation (3): \[ B + (4 - 2B) = 0 \quad \Rightarrow \quad 4 - B = 0 \quad \Rightarrow \quad B = 4 \] Then substituting back to find \(C\): \[ C = 4 - 2(4) = -4 \] ### Final Values Thus we have: - \(A = 0\) - \(B = 4\) - \(C = -4\) ### Conclusion Now we can check the statements: 1. **Statement 1**: \(A = 1\) → False 2. **Statement 2**: \(2B + C = 4\) → True (since \(2(4) - 4 = 4\)) 3. **Statement 3**: \(A + B + C = 0\) → True (since \(0 + 4 - 4 = 0\))
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