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Zorluk: KolayLinear Inequalities and Absolute Value

If 3x612|3x - 6| \le 12, which of the following inequality ranges represents all possible values of xx?

  1. 2x6-2 \le x \le 6Cevap
  2. B
    x6x \le 6
  3. C
    6x2-6 \le x \le 2
  4. D
    6x6-6 \le x \le 6
  5. E
    2x2-2 \le x \le 2

Cevap

2x6-2 \le x \le 6
The expression 3x612|3x - 6| \le 12 expands to the double inequality 123x612-12 \le 3x - 6 \le 12. Adding 66 to each part produces 63x18-6 \le 3x \le 18. Dividing all terms by 33 yields 2x6-2 \le x \le 6, which matches the correct solution range.

Adım Adım Çözüm

1
Rewrite the absolute value inequality as a compound inequality.
123x612-12 \le 3x - 6 \le 12
An absolute value inequality of the form uk|u| \le k (where k0k \ge 0) is equivalent to kuk-k \le u \le k.
2
Add 66 to all three parts of the inequality.
63x18-6 \le 3x \le 18
Isolate the term containing xx.
3
Divide all three parts of the inequality by 33.
2x6-2 \le x \le 6
Since 3>03 > 0, dividing by 33 isolates xx without flipping the inequality signs.

Anahtar Kavram

Solving Linear Absolute Value Inequalities
Tahmini Süre:45s
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