Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Indefinite Integration

Question:

Find $\int x e^{(1+x^2)} dx$.

Options:

$e^{(1+x^2)} + C$

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

$2e^{(1+x^2)} + C$

$x^2e^{(1+x^2)} + C$

Correct Answer:

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

Explanation:

The correct answer is Option (2) → $\frac{1}{2}e^{(1+x^2)} + C$

Let $I=\int x e^{(1+x^2)} dx$

Put $t = 1 + x^2$, then $dt = 2x dx ⇒\frac{dt}{2} = x dx$.

$∴I = \int e^t \frac{dt}{2} = \frac{1}{2} \int e^t dt$

$= \frac{1}{2} e^t + C = \frac{1}{2} e^{(1+x^2)} + C$