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Set 6: Linear Inequalities (Intermediate)

Explanation

Answer: A

Solve: 2x+19|2x + 1| \geq 9

A.

x4x \geq 4 or x5x \leq -5

✓ Correct
B.

5x4-5 \leq x \leq 4

C.

x4x \geq 4

D.

x5x \leq -5

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Absolute value \geq splits into two "or" inequalities. 1. Case 1: 2x+192x8x42x + 1 \geq 9 \rightarrow 2 x \geq 8 \rightarrow x \geq 4 2. Case 2: 2x+192x10x52x + 1 \leq -9 \rightarrow 2 x \leq -10 \rightarrow x \leq -5 3. Combine: x4x \geq 4 or x5x \leq -5 Strategic Tip: "GreatOR" = Or. Split into positive and negative cases, flipping the sign for the negative case. Choice B is incorrect because it models 2x+19|2 x+1| \leq 9 ("Less thAND"). Choice C is incorrect because it misses the negative case. Choice D is incorrect because it misses the positive case.

Key Steps:

The correct answer is x4x \geq 4 or x5x \leq -5

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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