Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Indefinite Integration

Question:

$\int \frac{x^3-3 x+7}{x^2+4} d x$ is equal to :

Options:

$\frac{x^2}{2}+\frac{7}{2} \ln \left(x^2+4\right)+c$

$\frac{x^2}{2}+\frac{7}{2} \tan ^{-1} \frac{x}{2}-\frac{7}{2} \ln \left(x^2+4\right)+c$

$-\frac{x^2}{2}+\frac{7}{2} \tan ^{-1} \frac{x^2}{2}+\frac{7}{2} \ln \left(x^2+4\right)+c$

$\frac{x}{2}+\frac{7}{2} \tan ^{-1} \frac{x}{2}+c$

Correct Answer:

$\frac{x^2}{2}+\frac{7}{2} \tan ^{-1} \frac{x}{2}-\frac{7}{2} \ln \left(x^2+4\right)+c$

Explanation:

$\frac{x^3-3 x+7}{x^2+4}=x-\frac{7(x-1)}{x^2+4}$

$\int \frac{x^3-3 x+7}{x^2+4} d x=\frac{x^2}{2}-7 \int \frac{(x-1)}{x^2+4} d x$

$=\frac{x^2}{2}+\frac{7}{2} \tan ^{-1} \frac{x}{2}-\frac{7}{2} \ln \left(x^2+4\right)+c$

Hence (2) is the correct answer.