Question

Difficulty: MediumLinear and Quadratic Inequalities

Which of the following is the set of real values of xx that satisfies the inequality 3x42x+53\frac{3 - x}{4} \le \frac{2x + 5}{3}?

  1. x1x \ge -1Answer
  2. B
    x1x \le -1
  3. C
    x1x \ge 1
  4. D
    x1x \le 1

Answer

The set of real values of xx that satisfies the inequality is x1x \ge -1.
Multiplying through by 12 gives 93x8x+209 - 3x \le 8x + 20. Grouping terms results in 11x11-11x \le 11. Dividing by 11-11 requires reversing the inequality sign from \le to \ge, giving the solution x1x \ge -1.

Step-by-Step Solution

1
Clear the denominators by multiplying both sides of the inequality by the lowest common multiple, 12.
3(3x)4(2x+5)3(3 - x) \le 4(2x + 5)
Eliminating fractions simplifies the algebraic expression.
2
Expand both sides by distributing the multipliers.
93x8x+209 - 3x \le 8x + 20
Prepares terms for grouping variables on one side and constants on the other.
3
Collect all terms containing xx on the left side and constant terms on the right side.
3x8x209    11x11-3x - 8x \le 20 - 9 \implies -11x \le 11
Isolates the linear variable term.
4
Divide both sides by 11-11 and flip the inequality sign.
x1x \ge -1
Dividing or multiplying an inequality by a negative number reverses the direction of the inequality sign.

Key Concept

Linear Inequalities and Reversing Inequality Sign on Division by Negative Numbers
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