Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main 201412 AprilOnline
Exam
JEE Main
Year
2014
Date
12 April
Mode
Online
Subject
Mathematics
Chapter
Continuity and Differentiability

JEE Main 2014 · 12 April · Online · Mathematics · Continuity and Differentiability

Let f, g: R arrow R be two functions defined by f(x)= cases x...

Let f,g:R→R\mathrm{f}, \mathrm{g}: \mathrm{R} \rightarrow \mathrm{R} be two functions defined by f(x)=f(x)=\begin{cases}x \sin \left(\frac{1}{x}\right) & , x \neq 0 \\ 0, & , x=0\end{cases}$andandg(x)=x f(x)StatementI:Statement I:fisacontinuousfunctionatis a continuous function at\mathrm{x}=0.StatementII:. Statement II:gisadifferentiablefunctionatis a differentiable function atx=0$.

Options

  1. ABoth statement I and II are false.
  2. BBoth statement I and II are true.
  3. CStatement I\mathrm{I} is true, statement II\mathrm{II} is false.
  4. DStatement I\mathrm{I} is false, statement II\mathrm{II} is true.

Correct answer

B. Both statement I and II are true.

Step-by-step solution

f(x)={xsin⁡(1x),x≠00,x=0 and  g(x)=xf(x) For  f(x)LHL=lim⁡h→0−{−hsin⁡(−1h)}\begin{aligned}&f(x)= \begin{cases} x \sin \left(\frac{1}{x}\right),& x ≠ 0 \\ 0, & x=0\end{cases} \\ &\text{\text{ and } } g(x)=x f(x) \\ &\text{\text{ For } } f(x) \\ &\mathrm{LHL}=\lim _{h \rightarrow 0^{-}} \left\{-h \sin \left(-\frac{1}{h}\right)\right\} \end{aligned}=0 ×afinitequantitybetween\times a finite quantity between-1 and 1=0RHL=lim⁡h→0+hsin⁡1h=0Also,1 =0 \mathrm{RHL}=\lim _{h \rightarrow 0^{+}}h \sin \frac{1}{h}=0 Also, f(0)=0ThusThus\mathrm{LHL}=\mathrm{RHL}== f(0)\therefore f(x)iscontinuousatis continuous atx=0g(x)=g(x)=\begin{cases}x^2 \sin \frac{1}{x},& x ≠ 0 \\ 0, & x=0\end{cases}$ForForg(x)\mathrm{LHL}=\lim _{h \rightarrow 0^{-}} \left\{-h^2 \sin \left(\frac{1}{h}\right)\right\}=02=0^2\times a finite quantity between −1and-1 and1=0\text{ RHL }=\lim _{h \rightarrow 0^{+}}h^2 \sin \left(\frac{1}{h}\right)=0 Alsog(0)=0∴g(x)g(0)=0\therefore g(x) is continuous at $x=0
Practice Continuity and Differentiability on Quantrex Academy →

More from Continuity and Differentiability

Let ℝ denote the set of all real numbers. Let f : ℝ arrow ℝ be an arbitrary function and… JEE Advanced 2026Consider the function f : (-(π)/(2), (π)/(2)) arrow (-∞, ∞) defined by f(x) = (|x| + |x… JEE Advanced 2026For a real number α , let [α] denote the greatest integer less than or equal to α . For a… JEE Advanced 2026For the function f(x) = e^ |x| - |x| , x ∈ ℝ , consider the following statements… JEE Main 2026Let f(x) = cases (1)/(3), & x ≤ π/2 (b(1- x))/((π-2x)^2), & x > π/2 cases . If f is… JEE Main 2026Let f(x) = cases x^3 + 8 ; & x Then the number of points, where the function g ∘ f is… JEE Main 2026Let f(x)= cases e^ x-1 , & x<0 x^2-5x+6, & x ≥ 0 cases and g(x)=f(|x|)+|f(x)| . If the… JEE Main 2026The number of points, at which the function f(x) = \ 6x, 2 + 3x^2\ + |x - 1|| |x^2… JEE Main 2026The number of points in the interval [2, 4] , at which the function f(x) = [x^2 - x… JEE Main 2026Let f(x)= _ θ arrow 0 ( π x-x^ ((2)/(θ)) (x-1) 1+x^ ((2)/(θ)) (x-1) ), x ∈ R . Consider… JEE Main 2026Let [t] denote the greatest integer less than or equal to t . If the function f(x)=\… JEE Main 2026If the function f(x)= e^ x (e^ x-x -1)+ _ e ( x+ x)-x x-x is continuous at x=0 , then the… JEE Main 2026Let α, β ∈ ℝ be such that the function f(x)= cases 2 α(x^ 2 -2)+2 β x &, x be… JEE Main 2026If f(x)=\ array cc a|x|+x^ 2 -2( |x|)( |x|) x &, x ≠ 0 b &, x=0 array . is continuous at… JEE Main 2026Let f(x)= cases a x^ 2 +2 a x+3 4 x^ 2 +4 x-3 &, x ≠-(3)/(2), (1)/(2) ~b &, x=-(3)/(2)… JEE Main 2026Let [·] denote the greatest integer function, and let f(x)= \ 2 x, x^ 2 \ . Let S = \ x… JEE Main 2026 Full Continuity and Differentiability list Continuity and Differentiability JEE Maths PYQsJEE Mathematics PYQs All JEE Main PYQs