Class CBSE Class 12 Mathematics Definite Integrals Q #635
KNOWLEDGE BASED
APPLY
1 Marks 2025 AISSCE(Board Exam) MCQ SINGLE
The value of \(\int_{0}^{1}\frac{dx}{e^{x}+e^{-x}}\) is:
(A) \(-\frac{\pi}{4}\)
(B) \(\frac{\pi}{4}\)
(C) \(\tan^{-1}e-\frac{\pi}{4}\)
(D) \(\tan^{-1}e\)
Correct Answer: C
Explanation
\[\frac{1}{e^{x}+e^{-x}} = \frac{1}{e^{x} + \frac{1}{e^{x}}} = \frac{1}{\frac{e^{2x} + 1}{e^x}} = \frac{e^x}{e^{2x} + 1}\]

The integral becomes:



\[I = \int_{0}^{1}\frac{e^x}{e^{2x} + 1}dx\]


Now use Substitution


Let \(u = e^x\). Then, \(du = e^x dx\).


Change the limits of integration:



  • Lower limit (\(x=0\)): \(u_1 = e^0 = 1\)

  • Upper limit (\(x=1\)): \(u_2 = e^1 = e\)



The integral becomes:



\[I = \int_{1}^{e}\frac{du}{u^{2} + 1}\]


Now evaluate and Apply Limits



\[I = \left[ \tan ^{-1}(u) \right]_{1}^{e}\]

\[=\tan ^{-1}(e) - \frac{\pi}{4}\]

AI Tutor Explanation

Powered by Gemini

Step-by-Step Solution

Let \(I = \int_{0}^{1}\frac{dx}{e^{x}+e^{-x}}\)

Multiply numerator and denominator by \(e^x\):

\(I = \int_{0}^{1}\frac{e^{x}}{e^{2x}+1}dx\)

Let \(u = e^x\), then \(du = e^x dx\)

When \(x = 0\), \(u = e^0 = 1\)

When \(x = 1\), \(u = e^1 = e\)

So, \(I = \int_{1}^{e}\frac{du}{u^{2}+1}\)

The integral of \(\frac{1}{u^2 + 1}\) is \(\tan^{-1}(u)\)

Therefore, \(I = [\tan^{-1}(u)]_{1}^{e}\)

\(I = \tan^{-1}(e) - \tan^{-1}(1)\)

Since \(\tan^{-1}(1) = \frac{\pi}{4}\)

\(I = \tan^{-1}(e) - \frac{\pi}{4}\)

Correct Answer: \(\tan^{-1}e-\frac{\pi}{4}\)

AI Suggestion: Option C

AI generated content. Review strictly for academic accuracy.

Pedagogical Audit
Bloom's Analysis: This is an APPLY question because it requires the student to apply integration techniques to solve the definite integral.
Knowledge Dimension: PROCEDURAL
Justification: The question requires the student to know and apply the correct procedure for evaluating definite integrals, including algebraic manipulation and the application of standard integral formulas.
Syllabus Audit: In the context of CBSE Class 12, this is classified as KNOWLEDGE. The question directly tests the student's knowledge of integration techniques as covered in the textbook.