Class CBSE Class 12 Mathematics Definite Integrals Q #636
KNOWLEDGE BASED
APPLY
1 Marks 2025 AISSCE(Board Exam) MCQ SINGLE
If \(f(2a-x)=f(x)\), then \(\int_{0}^{2a}f(x)dx\) is
(A) \(\int_{0}^{2a}f(\frac{x}{2})dx\)
(B) \(\int_{0}^{a}f(x)dx\)
(C) \(2\int_{a}^{0}f(x)dx\)
(D) \(2\int_{0}^{a}f(x)dx\)
Explanation
**Correct Option if MCQ:** D
**Reasoning:**
* Let \(I = \int_{0}^{2a}f(x)dx\).
* Using the property \(\int_{0}^{na}f(x)dx = n\int_{0}^{a}f(x)dx\) for \(f(x)=f(2a-x)\).
* Thus, \(I = 2\int_{0}^{a}f(x)dx\).

AI Tutor Explanation

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Step-by-Step Solution

Given \(f(2a-x) = f(x)\), we need to evaluate \(\int_{0}^{2a} f(x) dx\).

We can use the property of definite integrals: \(\int_{0}^{2a} f(x) dx = \int_{0}^{a} f(x) dx + \int_{a}^{2a} f(x) dx\).

Now, let's substitute \(x = 2a - t\) in the second integral, so \(dx = -dt\). When \(x = a\), \(t = a\), and when \(x = 2a\), \(t = 0\). Thus, \(\int_{a}^{2a} f(x) dx = \int_{a}^{0} f(2a - t) (-dt) = -\int_{a}^{0} f(2a - t) dt = \int_{0}^{a} f(2a - t) dt\).

Since \(f(2a - x) = f(x)\), we have \(f(2a - t) = f(t)\). Therefore, \(\int_{0}^{a} f(2a - t) dt = \int_{0}^{a} f(t) dt = \int_{0}^{a} f(x) dx\).

So, \(\int_{0}^{2a} f(x) dx = \int_{0}^{a} f(x) dx + \int_{0}^{a} f(x) dx = 2\int_{0}^{a} f(x) dx\).

Correct Answer: 2\int_{0}^{a}f(x)dx

AI Suggestion: Option D

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Pedagogical Audit
Bloom's Analysis: This is an APPLY question because it requires students to apply the property of definite integrals, specifically the property related to functions with symmetry about a certain point, to solve the given integral.
Knowledge Dimension: CONCEPTUAL
Justification: The question tests the understanding of the properties of definite integrals and how they relate to function symmetry, which is a conceptual understanding rather than a factual recall or procedural application.
Syllabus Audit: In the context of CBSE Class 12, this is classified as KNOWLEDGE. The question directly assesses the knowledge and application of properties of definite integrals as covered in the textbook.