8

Set 15: Linear Inequalities

Explanation

Answer: A

Solve: x+x=0|x| + x = 0

A.

x0x \leq 0

✓ Correct
B.

x=0x = 0

C.

x<0x < 0

D.

No solution

Detailed Explanation

Choice A is correct. Choice A is the correct answer. Analyze the definition of absolute value. 1. Equation: x=x|x| = -x 2. Definition: x=x|x| = -x is true if and only if xx is non-positive (x0x \leq 0). - If x=5x = -5: 5=(5)=5|-5| = -(-5) = 5 (True). - If x=0x = 0: 0=0=0|0| = -0 = 0 (True). - If x=5x = 5: 5=5|5| = -5 (False). 3. Result: x0x \leq 0 Strategic Tip: x=x|x| = x for x0x \geq 0. x=x|x| = -x for x0x \leq 0. Choice B is incorrect because it misses negative numbers. Choice C is incorrect because it misses 0. Choice D is incorrect because solutions exist.

Key Steps:

The correct answer is x0x \leq 0

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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