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JEE Main 20268 AprilEvening Shift
Exam
JEE Main
Year
2026
Date
8 April
Shift
Evening Shift
Subject
Mathematics
Chapter
Continuity and Differentiability

JEE Main 2026 · 8 April · Evening Shift · Mathematics · Continuity and Differentiability

For the function f(x) = e^ |x| - |x| , x ∈ ℝ , consider the...

For the function f(x)=esin⁡∣x∣−∣x∣f(x) = e^{\sin|x|} - |x|, x∈Rx \in \mathbb{R}, consider the following statements:
Statement I: ff is differentiable for all x∈Rx \in \mathbb{R}.
Statement II: ff is increasing in \left(-\pi, -\dfrac{\pi}{2}\right)$.
In the light of the above statements, choose the correct answer from the options given below:

Options

  1. ABoth Statement I and Statement II are true
  2. BBoth Statement I and Statement II are false
  3. CStatement I is true but Statement II is false
  4. DStatement I is false but Statement II is true

Correct answer

A. Both Statement I and Statement II are true

Step-by-step solution

For Statement I:
The given function is f(x)=esin⁡∣x∣−∣x∣f(x) = e^{\sin|x|} - |x|.
For x>0x > 0, f(x)=esin⁡x−xf(x) = e^{\sin x} - x.
Differentiating with respect to xx, we get:
f′(x)=esin⁡xcos⁡x−1f'(x) = e^{\sin x}\cos x - 1
The right-hand derivative at x=0x = 0 is:
f′(0+)=esin⁡0cos⁡0−1=1(1)−1=0f'(0^+) = e^{\sin 0}\cos 0 - 1 = 1(1) - 1 = 0

For x<0x < 0, f(x)=esin⁡(−x)−(−x)=e−sin⁡x+xf(x) = e^{\sin(-x)} - (-x) = e^{-\sin x} + x.
Differentiating with respect to xx, we get:
f′(x)=−e−sin⁡xcos⁡x+1f'(x) = -e^{-\sin x}\cos x + 1
The left-hand derivative at x=0x = 0 is:
f′(0−)=−e−sin⁡0cos⁡0+1=−1(1)+1=0f'(0^-) = -e^{-\sin 0}\cos 0 + 1 = -1(1) + 1 = 0

Since f′(0+)=f′(0−)=0f'(0^+) = f'(0^-) = 0, the function f(x)f(x) is differentiable at x=0x = 0. For all other x∈Rx \in \mathbb{R} (x≠0x \neq 0), the function is a composition of differentiable functions and is therefore differentiable. Thus, Statement I is true.

For Statement II:
We need to check the monotonicity of f(x)f(x) in the interval \left(-\pi, -\dfrac{\pi}{2}\right).<br>Since.<br>Sincex < 0inthisinterval,thederivativeis:<br>in this interval, the derivative is:<br>f'(x) = 1 - e^{-\sin x}\cos x<br>Intheinterval(−π,−π2)<br>In the interval \left(-\pi, -\dfrac{\pi}{2}\right) (which lies in the third quadrant), cos⁡x<0\cos x < 0.
Since e−sin⁡x>0ande^{-\sin x} > 0 and\cos x < 0,theterm, the term-e^{-\sin x}\cos x > 0.<br>Therefore,.<br>Therefore,f'(x) = 1 - e^{-\sin x}\cos x > 1 > 0.<br>Since.<br>Sincef'(x) > 0,thefunction, the functionf(x)isstrictlyincreasingin(−π,−π2)is strictly increasing in \left(-\pi, -\dfrac{\pi}{2}\right). Thus, Statement II is true.

Both Statement I and Statement II are true.

Answer: Both Statement I and Statement II are true
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