Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Indefinite Integration

Question:

The value of $\int\frac{\log[x+\sqrt{1+x^2}]}{\sqrt{1+x^2}}dx$ is:

Options:

$[\log(x+\sqrt{1+x^2})]^2$

$\frac{1}{4}[\log(x+\sqrt{1+x^2})]$

$\frac{1}{2}[\log(x+\sqrt{1+x^2})]^2$

None of these

Correct Answer:

$\frac{1}{2}[\log(x+\sqrt{1+x^2})]^2$

Explanation:

We know that $\int\frac{1}{\sqrt{1+x^2}}dx=\log(x+\sqrt{1+x^2})$

$∴\frac{d}{dx}\log(x+\sqrt{1+x^2})=\frac{1}{\sqrt{(1+x^2)}}$

$∴I=\int t\,dt=\frac{1}{2}t^2=\frac{1}{2}[\log(x+\sqrt{1+x^2})]^2$