Class CBSE Class 12 Mathematics Relations and Functions Q #959
COMPETENCY BASED
APPLY
0 Marks 2025 JEE Main 2025 MCQ SINGLE
Let A = { (α, β) ∈ R x R : |α - 1| ≤ 4 and |β - 5| ≤ 6} and B = { (α, β) ∈ R × R: 16(α-2)²+9(β-6)² ≤ 144}. Then
(A) A ⊂ B
(B) B ⊂ A
(C) neither A ⊂ B nor B ⊂ A
(D) A ∪ B = {(x, y) : -4 ≤ x ≤ 4, -1 ≤ y ≤ 11}
Correct Answer: B

AI Tutor Explanation

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Step-by-Step Solution

Step 1: Analyze set A

The inequalities defining set A are:

|α - 1| ≤ 4 => -4 ≤ α - 1 ≤ 4 => -3 ≤ α ≤ 5

|β - 5| ≤ 6 => -6 ≤ β - 5 ≤ 6 => -1 ≤ β ≤ 11

So, A represents a rectangle in the αβ-plane with vertices (-3, -1), (5, -1), (5, 11), and (-3, 11).

Step 2: Analyze set B

The inequality defining set B is:

16(α - 2)² + 9(β - 6)² ≤ 144

Divide by 144:

(α - 2)² / 9 + (β - 6)² / 16 ≤ 1

This represents an ellipse centered at (2, 6) with semi-major axis a = 4 (along the β-axis) and semi-minor axis b = 3 (along the α-axis).

Step 3: Compare the sets A and B

The rectangle A has α ranging from -3 to 5 and β ranging from -1 to 11.

The ellipse B is centered at (2, 6). The α values range from 2 - 3 = -1 to 2 + 3 = 5. The β values range from 6 - 4 = 2 to 6 + 4 = 10.

Since -1 ≥ -3 and 5 ≤ 5 for α, and 2 ≥ -1 and 10 ≤ 11 for β, the ellipse B is contained within the rectangle A. Therefore, B ⊂ A.

Step 4: Verify the options

(A) A ⊂ B is false because we found B ⊂ A.

(B) B ⊂ A is true.

(C) neither A ⊂ B nor B ⊂ A is false.

(D) A ∪ B = {(x, y) : -4 ≤ x ≤ 4, -1 ≤ y ≤ 11} is false. The correct union would be the rectangle A, which is {(α, β) : -3 ≤ α ≤ 5, -1 ≤ β ≤ 11}.

Correct Answer: B ⊂ A

AI Suggestion: Option B

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Pedagogical Audit
Bloom's Analysis: This is an APPLY question because it requires the student to apply their understanding of inequalities and geometric shapes (rectangles and ellipses) to determine the relationship between sets A and B. They need to manipulate the given inequalities and the equation of the ellipse to compare the regions they represent.
Knowledge Dimension: CONCEPTUAL
Justification: The question requires understanding the concepts of inequalities, absolute values, ellipses, and set theory (specifically subsets). It's not just about recalling facts but about understanding the relationships between these concepts.
Syllabus Audit: In the context of CBSE Class 12, this is classified as COMPETENCY. The question assesses the student's ability to apply their knowledge of coordinate geometry and inequalities to solve a problem involving sets, rather than simply recalling definitions or formulas.