Class CBSE Class 12 Mathematics Applications of Integrals Q #641
KNOWLEDGE BASED
APPLY
1 Marks 2025 AISSCE(Board Exam) MCQ SINGLE
The area of the region enclosed by the curve \(y=\sqrt{x}\) and the lines \(x=0\) and \(x=4\) and x-axis is:
(A) \(\frac{16}{9}\) sq. units
(B) \(\frac{32}{9}\) sq. units
(C) \(\frac{16}{3}\) sq. units
(D) \(\frac{32}{3}\) sq. units
Correct Answer: C
Explanation
The area (\(A\)) of the region enclosed by the curve \(y = f(x)\), the \(x\)-axis, and the vertical lines \(x=a\) and \(x=b\) is given by the definite integral:\[A = \int_{a}^{b} f(x) dx\]
\[A = \int_{0}^{4} x^{1/2} dx\]
\[A = \frac{2}{3} \left[ x^{3/2} \right]_{0}^{4}\]
\[A = \frac{2}{3} \left[ (4)^{3/2} - (0)^{3/2} \right]\]
\[A = \frac{16}{3}\]

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Step-by-Step Solution

The area enclosed by the curve \(y = \sqrt{x}\), the lines \(x=0\) and \(x=4\), and the x-axis can be found by integrating the function \(y = \sqrt{x}\) with respect to \(x\) from 0 to 4.

Area \(A = \int_{0}^{4} \sqrt{x} \, dx\)

Rewrite \(\sqrt{x}\) as \(x^{\frac{1}{2}}\):

\(A = \int_{0}^{4} x^{\frac{1}{2}} \, dx\)

Integrate \(x^{\frac{1}{2}}\) with respect to \(x\):

\(A = \left[ \frac{x^{\frac{3}{2}}}{\frac{3}{2}} \right]_{0}^{4}\)

Simplify:

\(A = \frac{2}{3} \left[ x^{\frac{3}{2}} \right]_{0}^{4}\)

Evaluate the definite integral:

\(A = \frac{2}{3} \left( 4^{\frac{3}{2}} - 0^{\frac{3}{2}} \right)\)

\(A = \frac{2}{3} \left( (4^{\frac{1}{2}})^3 - 0 \right)\)

\(A = \frac{2}{3} \left( 2^3 \right)\)

\(A = \frac{2}{3} \cdot 8\)

\(A = \frac{16}{3}\)

The area of the region is \(\frac{16}{3}\) square units.

Correct Answer: \(\frac{16}{3}\) sq. units

Pedagogical Audit
Bloom's Analysis: This is an APPLY question because it requires the student to apply the concept of definite integrals to calculate the area under a curve. The student must use the given function and limits to set up and solve the integral.
Knowledge Dimension: PROCEDURAL
Justification: The question requires the student to apply a specific procedure (integration) to find the area under the curve. It involves knowing the steps of integration and applying them correctly.
Syllabus Audit: In the context of CBSE Class 12, this is classified as KNOWLEDGE. The question directly tests the student's knowledge of applying integration to find the area under a curve, a standard topic covered in the textbook.
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AI Suggestion: Option C

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