Question

Difficulty: MediumSolving One-Variable Inequalities

Consider the following linear inequality:

3(x−2)−7x≥2(x+3)3(x - 2) - 7x \geq 2(x + 3)

Which of the following represents the correct solution set for xx?

  1. x≤−2x \leq -2Answer
  2. B
    x≥−2x \geq -2
  3. C
    x≤0x \leq 0
  4. D
    x≥6x \geq 6

Answer

The correct solution is x≤−2x \leq -2.
To find the solution, expand the terms to get 3x−6−7x≥2x+63x - 6 - 7x \geq 2x + 6. Combine the like terms on the left to form −4x−6≥2x+6-4x - 6 \geq 2x + 6. Subtracting 2x2x and adding 66 to both sides isolates the variable, resulting in −6x≥12-6x \geq 12. Finally, divide by −6-6. Because we are dividing by a negative number, the inequality sign must flip, giving the correct answer of x≤−2x \leq -2.

Step-by-Step Solution

1
Distribute the constants on both sides of the inequality.
3x−6−7x≥2x+63x - 6 - 7x \geq 2x + 6
Expanding the expressions clears the parentheses and allows us to combine like terms.
2
Combine the like terms on the left side of the inequality.
−4x−6≥2x+6-4x - 6 \geq 2x + 6
3x−7x3x - 7x simplifies to −4x-4x.
3
Move all terms containing xx to one side and constants to the other side.
−6x≥12-6x \geq 12
Subtracting 2x2x from both sides gives −6x−6≥6-6x - 6 \geq 6. Then, adding 66 to both sides isolates the variable term.
4
Divide both sides by −6-6 and reverse the inequality symbol.
x≤−2x \leq -2
When multiplying or dividing an inequality by a negative number, the inequality direction must be flipped to remain mathematically true.

Key Concept

Solving Linear Inequalities with Variables on Both Sides
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