Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Indefinite Integration

Question:

Find $\int \frac{2^{x+1} - 5^{x-1}}{10^x} dx$.

Options:

$\frac{2 \cdot 5^{-x}}{\ln 5} - \frac{2^{-x}}{5 \ln 2} + C$

$\frac{1}{5 \cdot 2^x \ln 2} - \frac{2}{5^x \ln 5} + C$

$\frac{1}{2^x \ln 2} - \frac{1}{5^x \ln 5} + C$

$-\frac{2}{5^x \ln 5} - \frac{1}{5 \cdot 2^x \ln 2} + C$

Correct Answer:

$\frac{1}{5 \cdot 2^x \ln 2} - \frac{2}{5^x \ln 5} + C$

Explanation:

The correct answer is Option (2) → $\frac{1}{5 \cdot 2^x \ln 2} - \frac{2}{5^x \ln 5} + C$

$I = \int \left( 2(5^{-x}) - \frac{1}{5}(2^{-x}) \right) dx$

$= -\frac{2}{5^x \log 5} + \frac{1}{5(2^x) \log 2} + C$