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Set 11: Linear Inequalities (Intermediate)

Explanation

Answer: A

Solve: 2(3x4)10-2(3x - 4) \leq 10

A.

x13x \geq -\frac{1}{3}

✓ Correct
B.

x13x \leq -\frac{1}{3}

C.

x13x \geq \frac{1}{3}

D.

x13x \leq \frac{1}{3}

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Distributing negative coefficients requires careful sign tracking. 1. Distribute: 2(3x)2(4)10-2(3 x) - 2(-4) \leq 10, giving 6x+810-6 x + 8 \leq 10 2. Subtract 8: 6x2-6 x \leq 2 3. Divide by -6: x26=13x \geq -\frac{2}{6} = -\frac{1}{3} (REVERSE!) Strategic Tip: When distributing a negative, every term inside changes sign. Then dividing by negative reverses the inequality. Choice B is incorrect because it fails to reverse the inequality when dividing by -6. Choice C is incorrect because it has the wrong sign on the fraction (should be negative). Choice D is incorrect because it combines wrong sign and wrong direction.

Key Steps:

The correct answer is x13x \geq -\frac{1}{3}

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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