Let {x} denote the fractional part of x and f(x)=fraccos^-1(1-\x\^2)sin^-1(1-\x\)\x\-\x\^3, xne0. If L and R respectively denotes the left hand limit and the right hand limit of f(x) at x=0 then frac32pi^2(L^2+R^2) is equal to

Numerical Answer Type:
Enter a numerical value Answer: 18 to 18 +4 marks

Solution & Explanation

### Related Formula Definition of fractional part function: - For x to 0^+, \x\ = x - 0 = x. - For x to 0^-, \x\ = x - (-1) = x + 1. ### Core Logic Let's evaluate the left-hand limit (L) and right-hand limit (R) separately by setting up substitution parameters around the point x=0. ### Step 1: Evaluate Right Hand Limit (R) As x to 0^+, substitute \x\ = h where h to 0: R = lim_h to 0 fraccos^-1(1-h^2)sin^-1(1-h)h(1-h^2) = lim_h to 0 fraccos^-1(1-h^2)h cdot left(fracsin^-111right) = fracpi2 lim_h to 0 fraccos^-1(1-h^2)h Let cos^-1(1-h^2) = theta implies 1-h^2 = costheta implies h^2 = 1 - costheta = 2sin^2(theta/2). As h to 0, theta to 0, so h approx fracthetasqrt2: R = fracpi2 lim_theta to 0 fracthetafracthetasqrt2 = fracpisqrt2 ### Step 2: Evaluate Left Hand Limit (L) As x to 0^-, let x = -h implies \x\ = 1-h where h to 0: L = lim_h to 0 fraccos^-1(1-(1-h)^2)sin^-1(1-(1-h))(1-h) - (1-h)^3 L = lim_h to 0 fraccos^-1(2h-h^2)sin^-1h(1-h)[1 - (1-h)^2] = lim_h to 0 fraccos^-1(0)sin^-1h1 cdot (2h-h^2) L = fracpi2 lim_h to 0 left( fracsin^-1hh cdot frac12-h right) = fracpi2 cdot 1 cdot frac12 = fracpi4 ### Step 3: Calculate the Target Value Substituting the computed limits L = fracpi4 and R = fracpisqrt2 into the target expression: frac32pi^2(L^2+R^2) = frac32pi^2 left( fracpi^216 + fracpi^22 right) = 32 left( frac116 + frac12 right) = 2 + 16 = 18 ### Pattern Recognition Sees: Discontinuous fractional part function framing an indeterminate limit form. Trap: Be extremely careful when managing fractional limits below zero: \x\ to 1 when x to 0^-, transforming expressions significantly compared to right-hand approaches. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Mathematics: Limits, Continuity and Differentiability Class 11 Mathematics: Relations and Functions

Reference Study Guides

More Limits, Continuity and Differentiability Previous-Year Questions — Page 9

Q17 jee_main_2024_31_jan_morning Continuity Check
Let g(x) be a linear function and f(x) = begincases g(x) & , x le 0 \\ left(frac1+x2+xright)^frac1x & , x > 0 endcases is continuous at x = 0. If f'(1) = f(-1), then the value of g(3) is
  • A. frac13 log_e left(frac49e^1/3right)
  • B. frac13 log_e left(frac49right) + 1
  • C. log_e left(frac49right) - 1
  • D. log_e left(frac49e^1/3right)

Solution

### Core Logic Let g(x) = ax + b. Since f(x) is continuous at x = 0: lim_x to 0^+ f(x) = f(0) lim_x to 0 left(frac1+x2+xright)^frac1x = b As x to 0, the base approaches frac12, and exponent approaches infty. Thus, left(frac12right)^infty = 0. So, b = 0. Thus, g(x) = ax. ### Step 1: Calculate Derivative For x > 0, f(x) = left(frac1+x2+xright)^frac1x. Let y = f(x). ln y = frac1x lnleft(frac1+x2+xright) Differentiating both sides w.r.t x: frac1y y' = -frac1x^2 lnleft(frac1+x2+xright) + frac1x cdot frac2+x1+x cdot frac1(2+x) - (1+x)1(2+x)^2 y' = y left[ -frac1x^2 lnleft(frac1+x2+xright) + frac1x(1+x)(2+x) right] ### Step 2: Apply Condition At x=1, y = f(1) = frac23. f'(1) = frac23 left[ -1 lnleft(frac23right) + frac16 right] = -frac23 lnleft(frac23right) + frac19 Also f(-1) = g(-1) = -a. Given f'(1) = f(-1) implies -a = -frac23 lnleft(frac23right) + frac19. a = frac23 lnleft(frac23right) - frac19 ### Step 3: Evaluate g(3) g(3) = 3a = 2 lnleft(frac23right) - frac13 g(3) = lnleft(frac49right) - frac13 = lnleft(frac49right) - ln(e^1/3) = lnleft(frac49e^1/3right) ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 12 Maths: Continuity and Differentiability Class 12 Maths: Application of Derivatives

More Limits, Continuity and Differentiability Questions — jee_main_2024_01_february_morning

Practice all Limits, Continuity and Differentiability previous-year questions →

Rankbit System
JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%) | JEE Physics: Waves (+15.5%) | Electrostatics: Concentric Shells (-29.7%) | Modern Physics: Photoelectric Clones (+34.2%) | Mathematics: Definite Integrals (+18.1%) | Chemistry: Coordination Splitting (-11.4%)