Question:

The integral $\int \frac{e^{3\log_e{2x}} + 5e^{2\log_e{2x}}}{e^{4\log_e{x}} + 5e^{3\log_e{x}} - 7e^{2\log_e{x}}} \,dx$, x>0, is equal to: (where c is a constant of integration)

Show Hint

When integrating a rational function, first simplify any complex expressions (like exponential or logarithmic forms). Then, always check if the numerator is a multiple of the derivative of the denominator. If it is, the integral is simply a logarithm.
Updated On: Jan 3, 2026
  • $\log_e |x^2+5x-7| + c$
  • $4\log_e |x^2+5x-7| + c$
  • $\frac{1}{4}\log_e |x^2+5x-7| + c$
  • $\log_e \sqrt{x^2+5x-7} + c$
Hide Solution
collegedunia
Verified By Collegedunia

The Correct Option is B

Solution and Explanation

Simplify numerator: \[ e^{3\ln(2x)}=(2x)^3=8x^3,\quad 5e^{2\ln(2x)}=20x^2 \] Denominator: \[ x^4+5x^3-7x^2 \] \[ I=\int\frac{8x^3+20x^2}{x^4+5x^3-7x^2}\,dx =\int\frac{4(2x+5)}{x^2+5x-7}\,dx \] Let \(u=x^2+5x-7\Rightarrow du=(2x+5)dx\) \[ I=4\int\frac{du}{u} =4\ln|x^2+5x-7|+C \] Correct option: (B)
Was this answer helpful?
0
0