Question

Difficulty: EasyLinear Inequalities and Absolute Value

What is the least integer value of xx that satisfies the inequality 4x511|4x - 5| \le 11?

Answer: -1

Answer

The least integer value of xx that satisfies the inequality is 1-1.
Expanding the absolute value inequality 4x511|4x - 5| \le 11 produces 114x511-11 \le 4x - 5 \le 11. Adding 5 across all sections yields 64x16-6 \le 4x \le 16, and dividing by 4 results in 1.5x4-1.5 \le x \le 4. The set of integers within this range is {1,0,1,2,3,4}\{-1, 0, 1, 2, 3, 4\}, making 1-1 the least integer value.

Step-by-Step Solution

1
Rewrite the absolute value inequality as a double inequality.
114x511-11 \le 4x - 5 \le 11
An absolute value inequality of the form ua|u| \le a for a0a \ge 0 is equivalent to aua-a \le u \le a.
2
Add 5 to all parts of the compound inequality.
64x16-6 \le 4x \le 16
To isolate xx, first add 5 to eliminate the constant term 5-5.
3
Divide all parts by 4.
1.5x4-1.5 \le x \le 4
Dividing by a positive constant preserves the direction of the inequality signs.
4
Select the minimum integer contained within the solution interval [1.5,4][-1.5, 4].
1-1
The integer values satisfying 1.5x4-1.5 \le x \le 4 are 1,0,1,2,3,4-1, 0, 1, 2, 3, 4. The smallest among these is 1-1.

Key Concept

Linear inequalities involving absolute value
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