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Zorluk: KolayReal Numbers, Number Line, and Absolute Value

On the real number line, xx is a real number such that x+25|x + 2| \le 5. Which of the following could be the value of xx? Select all such values.

  1. A
    8-8
  2. 7-7Cevap
  3. 00Cevap
  4. 33Cevap
  5. E
    44

Cevap

The values that satisfy the inequality are 7-7, 00, and 33.
The inequality x+25|x + 2| \le 5 represents all real numbers xx whose distance from 2-2 on the number line is at most 55. This gives the closed interval [7,3][-7, 3]. The values 7-7, 00, and 33 all fall within this range.

Adım Adım Çözüm

1
Set up the compound inequality for the absolute value expression.
5x+25-5 \le x + 2 \le 5
For any real number expression AA and non-negative constant kk, Ak|A| \le k is equivalent to kAk-k \le A \le k.
2
Isolate xx by subtracting 22 from all parts of the inequality.
52x52    7x3-5 - 2 \le x \le 5 - 2 \implies -7 \le x \le 3
Subtracting a constant from all parts preserves the inequality signs.
3
Evaluate which given choices lie within the interval [7,3][-7, 3].
7-7, 00, and 33 lie within [7,3][-7, 3], while 8-8 and 44 lie outside.
Only values inside or on the boundaries of [7,3][-7, 3] satisfy the inequality.

Anahtar Kavram

Absolute Value Inequalities and Real Number Line Distance
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