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Set 6: Linear Inequalities

Explanation

Answer: A

Which system defines a square of side length 2 centered at the origin?

A.

x1,y1|x| \leq 1, |y| \leq 1

✓ Correct
B.

x2,y2|x| \leq 2, |y| \leq 2

C.

x2+y24x^2 + y^2 \leq 4

D.

x+y1|x| + |y| \leq 1

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Analyze boundaries. 1. Side length 2: Means extending 1 unit from center in each direction. 2. X-bounds: 1x1x1-1 \leq x \leq 1 \rightarrow |x| \leq 1 3. Y-bounds: 1y1y1-1 \leq y \leq 1 \rightarrow |y| \leq 1 Strategic Tip: xa|x| \leq a creates a vertical strip width 2a2a. ya|y| \leq a creates a horizontal strip. Choice B is incorrect because side length is 4. Choice C is incorrect because it is a circle. Choice D is incorrect because it is a diamond (rotated square).

Key Steps:

The correct answer is x1,y1|x| \leq 1, |y| \leq 1

Why others are wrong:
B: Choice B is incorrect and may result from a calculation error.
C: Choice C is incorrect and may result from a calculation error.
D: Choice D is incorrect and may result from a calculation error.

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