Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Indefinite Integration

Question:

Integrate the function w.r.t. $x$: $2x \sin (x^2 + 1)$

Options:

$-\cos (x^2 + 1) + C$

$\cos (x^2 + 1) + C$

$2\cos (x^2 + 1) + C$

$-\frac{1}{2}\cos (x^2 + 1) + C$

Correct Answer:

$-\cos (x^2 + 1) + C$

Explanation:

The correct answer is Option (1) → $-\cos (x^2 + 1) + C$

Derivative of $x^2 + 1$ is $2x$. Thus, we use the substitution $x^2 + 1 = t$ so that $2x \, dx = dt$.

Therefore, $\int 2x \sin (x^2 + 1) \, dx = \int \sin t \, dt = -\cos t + C = -\cos (x^2 + 1) + C$