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Let f(x) = begincases (1 + ax)^1/x & , x < 0 \\ 1 + b & , x = 0 \\ frac(x + 4)^1/2 - 2(x + c)^1/3 - 2 & , x > 0 endcases [cite: 680] be continuous at x = 0[cite: 681]. Then mathrme^mathrmacdot b cdot c is equal to[cite: 681]:

Solution & Explanation

### Related Formula Continuity definition condition frame: lim_x rightarrow 0^- f(x) = f(0) = lim_x rightarrow 0^+ f(x) ### Core Logic Evaluate Left-Hand Limit (LHL) using standard forms [cite: 1410]: textLHL = lim_x rightarrow 0^- (1+ax)^1/x = e^a [cite: 1410] Given baseline definition states f(0) = 1+b [cite: 1410]. For Right-Hand Limit (RHL) to be finite and valid, the numerator tracking towards 0 means the denominator must also balance towards 0 to avoid divergence [cite: 1411]: lim_x rightarrow 0^+ left[(x+c)^1/3 - 2right] = 0 implies c^1/3 = 2 implies c = 8 [cite: 1414] ### Step 1: Applying L'Hopital's rule to the RHL With c=8, evaluate RHL limit expressions using derivatives [cite: 1411]: textRHL = lim_x rightarrow 0^+ fracfrac12sqrtx+4frac13(x+8)^-2/3 = fracfrac12(2)frac13(8)^-2/3 = fracfrac14frac13 cdot 4 = frac14 cdot 12 = 3 [cite: 1411, 1415] ### Step 2: Equating limits for parameter solutions Equate continuous criteria milestones together [cite: 1416]: e^a = 1 + b = 3 [cite: 1416] e^a = 3 implies b = 2 [cite: 1416] Compute the ultimate target combination product configuration [cite: 1416]: e^a cdot b cdot c = 3 cdot 2 cdot 8 = 48 [cite: 1416] ### Pattern Recognition Determining missing root constants inside indeterminate fraction structures handles calculations swiftly before running formal limits. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Limits, Continuity and Differentiability

More Limits, Continuity and Differentiability Previous-Year Questions — Page 5

Q65 2025 Limits of Special Series
The value of lim_nto inftyleft(sum_K = 1^nfrack^3 + 6k^2 + 11k + 5(k + 3)!right) is:
  • A. \frac{4}{3}
  • B. 2
  • C. \frac{7}{3}
  • D. \frac{5}{3}

Solution

### Related Formula sum_k=1^infty left( frac1k! - frac1(k+3)! right) implies textTelescoping Series simplification ### Core Logic Rewrite the numerator polynomial to establish factor terms matching the factorial expansion base (k+3): k^3 + 6k^2 + 11k + 5 = (k^3 + 6k^2 + 11k + 6) - 1 = (k+1)(k+2)(k+3) - 1 ### Step 1: Simplify General Term T_k = frac(k+1)(k+2)(k+3)(k+3)! - frac1(k+3)! T_k = frac1k! - frac1(k+3)! This creates a clean telescoping layout format structure. ### Step 2: Sum the Series Writing out expanded \partial sums up to infinity: S = left( frac11! + frac12! + frac13! + frac14! + dots right) - left( frac14! + frac15! + frac16! + dots right) All higher terms cancel out systematically, leaving exactly the leading remaining fragments: S = frac11! + frac12! + frac13! = 1 + frac12 + frac16 = frac106 = frac53 ### Pattern Recognition Whenever factorials dominate fraction denominators, manipulate structural terms to align components via Telescoping sums (V_n - V_n-k). ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Mathematics: Limits, Continuity and Differentiability Class 11 Mathematics: Sequences and Series

More Limits, Continuity and Differentiability Questions — jee_main_2025_03_april_morning

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