JEE Advanced 2026Paper 1
- Exam
- JEE Advanced
- Year
- 2026
- Paper
- Paper 1
- Subject
- Mathematics
- Chapter
- Continuity and Differentiability
JEE Advanced 2026 · Paper 1 · Mathematics · Continuity and Differentiability
Consider the function f : (-(π)/(2), (π)/(2)) arrow (-∞, ∞) defined...
Consider the function defined by
,
where is the greatest integer less than or equal to .
Let be the total number of points in the interval \left(-\dfrac{\pi}{2}, \dfrac{\pi}{2}\right)f\beta at which is NOT differentiable.
Then the value of is ___________.
,
where is the greatest integer less than or equal to .
Let be the total number of points in the interval \left(-\dfrac{\pi}{2}, \dfrac{\pi}{2}\right)f\beta at which is NOT differentiable.
Then the value of is ___________.
Correct answer
0
Step-by-step solution
Let , where and .
First, we analyze on the interval \left(-\dfrac{\pi}{2}, \dfrac{\pi}{2}\right)y = x \sin xx \in \left[0, \dfrac{\pi}{2}\right)x \sin xx = 0x \sin x = 0x \to \dfrac{\pi}{2}x \sin x \to \dfrac{\pi}{2} \approx 1.57x \sin x \in [0, 1.57)x \in \left(-\dfrac{\pi}{2}, \dfrac{\pi}{2}\right)[x \sin x]00 \le x \sin x < 111 \le x \sin x < \dfrac{\pi}{2}x_1 \in \left(0, \dfrac{\pi}{2}\right)x_1 \sin x_1 = 1-x_1 where .
Therefore, has jump discontinuities at exactly two points: and .
At , and is non-negative in its neighborhood, so around , making continuous and differentiable at .
Next, we analyze .
The absolute value functions have critical points at and .
For in a small neighborhood of (specifically ):
If , .
If , .
Since , is differentiable at .
For in a small neighborhood of :
If , .
If , .
Since , is not differentiable at .
Now, combining the results for :
1. Discontinuities: is continuous everywhere. is discontinuous at and . Thus, is discontinuous at points. .
2. Non-differentiability: is not differentiable where it is discontinuous ( and ). Additionally, at , is constant () because , meaning is differentiable at . However, is not differentiable at . Thus, is not differentiable at .
This gives points of non-differentiability: . .
Finally, .
Answer:
First, we analyze on the interval \left(-\dfrac{\pi}{2}, \dfrac{\pi}{2}\right)y = x \sin xx \in \left[0, \dfrac{\pi}{2}\right)x \sin xx = 0x \sin x = 0x \to \dfrac{\pi}{2}x \sin x \to \dfrac{\pi}{2} \approx 1.57x \sin x \in [0, 1.57)x \in \left(-\dfrac{\pi}{2}, \dfrac{\pi}{2}\right)[x \sin x]00 \le x \sin x < 111 \le x \sin x < \dfrac{\pi}{2}x_1 \in \left(0, \dfrac{\pi}{2}\right)x_1 \sin x_1 = 1-x_1 where .
Therefore, has jump discontinuities at exactly two points: and .
At , and is non-negative in its neighborhood, so around , making continuous and differentiable at .
Next, we analyze .
The absolute value functions have critical points at and .
For in a small neighborhood of (specifically ):
If , .
If , .
Since , is differentiable at .
For in a small neighborhood of :
If , .
If , .
Since , is not differentiable at .
Now, combining the results for :
1. Discontinuities: is continuous everywhere. is discontinuous at and . Thus, is discontinuous at points. .
2. Non-differentiability: is not differentiable where it is discontinuous ( and ). Additionally, at , is constant () because , meaning is differentiable at . However, is not differentiable at . Thus, is not differentiable at .
This gives points of non-differentiability: . .
Finally, .
Answer: