4

Set 3: Linear Inequalities (Advanced)

Explanation

Answer: A

A number nn is at least 5 and less than 12. Which inequality represents this?

A.

5n<125 \leq n < 12

✓ Correct
B.

5<n125 < n \leq 12

C.

5n125 \leq n \leq 12

D.

5<n<125 < n < 12

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Translate the phrases to symbols. 1. "At least 5": n5n \geq 5 or 5n5\leq n 2. "Less than 12": n<12n < 12 3. Combine: 5n<125\leq n < 12 Strategic Tip: Pay close attention to "strict" (<,><, >) vs "inclusive" (,\leq, \geq) phrases. Choice B is incorrect because it swaps the inclusive/strict conditions. Choice C is incorrect because it includes 12 ("less than or equal to"). Choice D is incorrect because it excludes 5 ("greater than").

Key Steps:

The correct answer is 5n<125\leq n < 12

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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