Class CBSE Class 12 Mathematics Definite Integrals Q #1707
COMPETENCY BASED
APPLY
1 Marks 2026 AISSCE(Board Exam) MCQ SINGLE
$\int_{-1}^{1}(1-|x|)dx$ is equal to:
(A) $2\int_{0}^{1}(1+x)dx$
(B) $0$
(C) $2\int_{-1}^{0}(1+x)dx$
(D) $2\int_{-1}^{0}(1-x)dx$
Correct Answer: C

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Detailed Solution

Step 1: Analyze the integrand

The integrand is $f(x) = 1 - |x|$. We observe that $f(-x) = 1 - |-x| = 1 - |x| = f(x)$. Since the function is even, the integral over the symmetric interval $[-1, 1]$ can be simplified as: $$ \int_{-1}^{1} (1 - |x|) dx = 2 \int_{0}^{1} (1 - |x|) dx $$

Step 2: Evaluate the integral using properties

Alternatively, consider the symmetry of the function $f(x) = 1 - |x|$. The graph is symmetric about the y-axis. The area under the curve from $-1$ to $1$ is twice the area from $-1$ to $0$ or twice the area from $0$ to $1$. In the interval $[-1, 0]$, $|x| = -x$. Therefore, the integrand becomes $1 - (-x) = 1 + x$. Thus, the integral can be written as: $$ \int_{-1}^{1} (1 - |x|) dx = 2 \int_{-1}^{0} (1 + x) dx $$

Step 3: Compare with options

Comparing our result $2 \int_{-1}^{0} (1 + x) dx$ with the given options, we find that it matches option (C).

Final Answer: C

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Pedagogical Audit
Bloom's Analysis: This is an APPLY question because the student must apply properties of definite integrals and the definition of the absolute value function to transform the expression.
Knowledge Dimension: PROCEDURAL
Justification: The question requires the execution of a sequence of steps involving integral properties and algebraic manipulation of absolute values.
Syllabus Audit: In the context of CBSE Class 12, this is classified as COMPETENCY. This question tests the conceptual understanding of definite integrals of modulus functions rather than rote calculation.