Using the properties of inequality, justify both steps in solving the inequality 2/5m - 7 ≤ 17.

1 answer

To solve the inequality \( \frac{2}{5}m - 7 \leq 17 \), we will perform two steps and provide justification for each step using properties of inequalities.

Step 1: Add 7 to both sides

Inequality: \[ \frac{2}{5}m - 7 \leq 17 \]

Justification: Adding the same number (in this case, 7) to both sides of an inequality preserves the direction of the inequality. This property states that if \( a \leq b \), then \( a + c \leq b + c \) for any real number \( c \).

New Inequality: \[ \frac{2}{5}m - 7 + 7 \leq 17 + 7 \]

Simplifying: \[ \frac{2}{5}m \leq 24 \]

Step 2: Multiply both sides by \( \frac{5}{2} \)

Inequality: \[ \frac{2}{5}m \leq 24 \]

Justification: When multiplying both sides of an inequality by a positive number, the direction of the inequality remains unchanged. This is a fundamental property of inequalities: if \( a \leq b \) and \( c > 0 \), then \( ac \leq bc \).

New Inequality: \[ \frac{5}{2} \cdot \frac{2}{5}m \leq 24 \cdot \frac{5}{2} \]

Simplifying: On the left side, the \( \frac{5}{2} \) and \( \frac{2}{5} \) cancel out, leaving \( m \): \[ m \leq 60 \]

Conclusion:

The solution to the original inequality \( \frac{2}{5}m - 7 \leq 17 \) is \( m \leq 60 \). Each step followed proper properties of inequalities, ensuring the integrity of the solution.