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JEE Main 20265 AprilMorning Shift
Exam
JEE Main
Year
2026
Date
5 April
Shift
Morning Shift
Subject
Mathematics
Chapter
Functions

JEE Main 2026 · 5 April · Morning Shift · Mathematics · Functions

The sum of all the integral values of p such that the equation 3 ^2...

The sum of all the integral values of pp such that the equation 3sin⁡2x+12cos⁡x−3=p3\sin^2 x + 12\cos x - 3 = p, x∈Rx \in \mathbb{R}, has at least one solution, is:

Options

  1. A−54-54
  2. B−60-60
  3. C−75-75
  4. D−84-84

Correct answer

C. −75-75

Step-by-step solution

Given equation: 3sin⁡2x+12cos⁡x−3=p3\sin^2 x + 12\cos x - 3 = p

Substituting sin⁡2x=1−cos⁡2x\sin^2 x = 1 - \cos^2 x:

3(1−cos⁡2x)+12cos⁡x−3=p3(1 - \cos^2 x) + 12\cos x - 3 = p

−3cos⁡2x+12cos⁡x=p-3\cos^2 x + 12\cos x = p

Let cos⁡x=t\cos x = t. Since x∈Rx \in \mathbb{R}, t∈[−1,1]t \in [-1, 1].

The equation becomes p=−3t2+12tp = -3t^2 + 12t.

Let f(t)=−3t2+12tf(t) = -3t^2 + 12t.

Differentiating with respect to tt:

f′(t)=−6t+12=6(2−t)f'(t) = -6t + 12 = 6(2 - t)

For t∈[−1,1]t \in [-1, 1], f′(t)>0f'(t) > 0, which means f(t)f(t) is strictly increasing in the interval [−1,1][-1, 1].

The minimum value of f(t)f(t) occurs at t=−1t = -1:

f(−1)=−3(−1)2+12(−1)=−15f(-1) = -3(-1)^2 + 12(-1) = -15

The maximum value of f(t)f(t) occurs at t=1t = 1:

f(1)=−3(1)2+12(1)=9f(1) = -3(1)^2 + 12(1) = 9

Thus, the range of pp for which the equation has at least one solution is [−15,9][-15, 9].

The integral values of pp are −15,−14,−13,…,9-15, -14, -13, \dots, 9.

The sum of these integral values is:

∑k=−159k=(−15)+(−14)+(−13)+(−12)+(−11)+(−10)+∑k=−99k\sum_{k=-15}^{9} k = (-15) + (-14) + (-13) + (-12) + (-11) + (-10) + \sum_{k=-9}^{9} k

Since ∑k=−99k=0\sum_{k=-9}^{9} k = 0, the sum simplifies to:

−15−14−13−12−11−10=−75-15 - 14 - 13 - 12 - 11 - 10 = -75

Answer: −75-75
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