Question

Difficulty: MediumSolving Linear Inequalities

What is the greatest integer value of xx that satisfies the inequality 7−5x3−4≥2(x+6)\frac{7 - 5x}{3} - 4 \ge 2(x + 6)?

Answer: -4

Answer

The greatest integer value of xx that satisfies the inequality is −4-4.
To find the greatest integer value of xx that satisfies the inequality, solve the inequality algebraically. First, clear the fraction by multiplying all terms by 3: 7−5x−12≥6(x+6)7 - 5x - 12 \ge 6(x + 6). Simplify the left side to −5x−5-5x - 5 and distribute the right side to get 6x+366x + 36. Move variables to the left side by subtracting 6x6x to get −11x−5≥36-11x - 5 \ge 36. Add 5 to both sides to get −11x≥41-11x \ge 41. Finally, divide by −11-11 and reverse the inequality sign, yielding x≤−4111x \le -\frac{41}{11}, which is approximately x≤−3.73x \le -3.73. The greatest integer less than or equal to −3.73-3.73 is −4-4.

Step-by-Step Solution

1
Multiply the entire inequality by 3 to clear the fraction
7−5x−12≥6(x+6)7 - 5x - 12 \ge 6(x + 6)
Multiplying by the common denominator eliminates the fraction and simplifies further algebraic steps.
2
Simplify the left side and distribute the right side
−5x−5≥6x+36-5x - 5 \ge 6x + 36
Combines constant terms on the left side and expands the parentheses on the right side.
3
Subtract 6x6x from both sides
−11x−5≥36-11x - 5 \ge 36
Gathers all variable terms on the left side of the inequality.
4
Add 5 to both sides
−11x≥41-11x \ge 41
Isolates the variable term by moving the constant to the right side.
5
Divide by -11 and reverse the inequality sign
x≤−4111x \le -\frac{41}{11}
Isolates the variable xx. Reversing the inequality sign is required when multiplying or dividing both sides by a negative number.
6
Determine the greatest integer satisfying the inequality
x≤−3.73x \le -3.73, so the greatest integer is −4-4
Since −4111≈−3.73-\frac{41}{11} \approx -3.73, the largest integer that is less than or equal to this value is −4-4.

Key Concept

Solving linear inequalities, applying the sign-flip rule when dividing by a negative number, and identifying integer boundaries.
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