Q82 / 150 · MHT CET 2025 (20 Apr Shift 2) · Mathematics

$\int e^x \frac{(x-1)}{(x+1)^3} \mathrm{~d} x=$

  • A
    $\mathrm{e}^x(x+1)^2+\mathrm{c}, \quad$ where c is the constant of integration
  • B
    $\mathrm{e}^x(x+1)^3+\mathrm{c}$, where c is the constant of integration
  • Correct answer
    C
    $\frac{\mathrm{e}^x}{(x+1)^2}+\mathrm{c}, \quad$ where c is the constant of integration
  • D
    $\frac{\mathrm{e}^x}{(x+1)^3}+\mathrm{c}, \quad$ where c is the constant of integration

Solution

Evaluate the integral $\int e^x \frac{x-1}{(x+1)^3} \mathrm{d} x$ using the standard formula $\int e^x [f(x) + f'(x)] \mathrm{d}x = e^x f(x) + C$.

Express the integrand in the appropriate form by rewriting the numerator:

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

Let $f(x) = \frac{1}{(x+1)^2}$
Then $f'(x) = -\frac{2}{(x+1)^3}$
Thus the integrand becomes $f(x) + f'(x)$

Applying the formula yields:

$\int e^x \left[\frac{1}{(x+1)^2} - \frac{2}{(x+1)^3}\right] \mathrm{d} x = e^x \cdot \frac{1}{(x+1)^2} + C = \frac{e^x}{(x+1)^2} + C$

This corresponds to option C.

Hence, the correct answer is option: 'C'.

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