9

Set 11: Linear Inequalities

Explanation

Answer: A

If 1.5x+2.40.9x+65x + 2.4 \leq 0.9x + 6, what is the solution?

A.

x6x \leq 6

✓ Correct
B.

x6x \geq 6

C.

x4x \leq 4

D.

x4x \geq 4

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Decimals follow the same rules as whole numbers. 1. Subtract 0.9 x: 1.5x0.9x+2.461.5x - 0.9 x + 2.4 \leq 6, giving 0.6x+2.460.6x + 2.4 \leq 6 2. Subtract 2.4: 0.6x3.60.6x \leq 3.6 3. Divide by 0.6: x6x \leq 6 Strategic Tip: Alternatively, multiply everything by 10 to eliminate decimals: 15x+249x+6015x + 24 \leq 9 x + 60. Choice B is incorrect because it reverses the direction without cause. Choice C is incorrect because it might come from dividing 2.4 by 0.6 without subtracting first. Choice D is incorrect because it combines wrong value and wrong direction.

Key Steps:

The correct answer is x6x \leq 6

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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