Question:

The integral $\int \frac{e^x (1 + x)}{\cos^2(x e^x)} \, dx =$

Show Hint

The derivative of $x e^x$ is $e^x(x+1)$. Seeing this combination in any integrand strongly suggests substituting $u = x e^x$.
Updated On: May 31, 2026
  • $\tan(x e^x) + C$
  • $-\tan(x e^x) + C$
  • $\cot(x e^x) + C$
  • $-\cot(x e^x) + C$
Show Solution
collegedunia
Verified By Collegedunia

The Correct Option is A

Solution and Explanation


Step 1: Concept

We use the method of substitution by identifying the derivative of the angle argument $x e^x$ in the numerator.

Step 2: Meaning

The derivative of $x e^x$ with respect to $x$ using the product rule is $e^x(1 + x)$. This matches the numerator exactly.

Step 3: Analysis

Let: \[ u = x e^x \implies du = (1 \cdot e^x + x \cdot e^x) \, dx = e^x (1 + x) \, dx \] Substitute these into the integral: \[ I = \int \frac{du}{\cos^2 u} = \int \sec^2 u \, du \] Using the standard integration formula $\int \sec^2 u \, du = \tan u + C$: \[ I = \tan u + C = \tan(x e^x) + C \]

Step 4: Conclusion

The value of the indefinite integral is $\tan(x e^x) + C$. Final Answer: (A)
Was this answer helpful?
0
0