Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Indefinite Integration

Question:

$\int\frac{(x-1)e^x}{x^2}dx, x> 0$ equals (where C is an arbitrary constant)

Options:

$xe^x+C$

$\frac{e^x}{x}+C$

$\frac{e^{-x}}{x^2}+C$

$e^x+\frac{1}{x}+C$

Correct Answer:

$\frac{e^x}{x}+C$

Explanation:

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

Integral: $\int \frac{(x-1)e^x}{x^2} \, dx$

Split the fraction: $\frac{(x-1)e^x}{x^2} = \frac{xe^x}{x^2} - \frac{e^x}{x^2} = \frac{e^x}{x} - \frac{e^x}{x^2}$

So: $\int \frac{(x-1)e^x}{x^2} \, dx = \int \frac{e^x}{x} \, dx - \int \frac{e^x}{x^2} \, dx$

Use formula: $\int \frac{e^x}{x^2} \, dx = -\frac{e^x}{x} + \int \frac{e^x}{x} \, dx$

Then: $\int \frac{e^x}{x} \, dx - \int \frac{e^x}{x^2} \, dx = \int \frac{e^x}{x} \, dx - \left(-\frac{e^x}{x} + \int \frac{e^x}{x} \, dx \right) = \frac{e^x}{x}$

Answer: $\frac{e^x}{x} + C$