Question

Find the student’s error in solving the following inequality.

Answer 1

Student's error is –5 < x.

Solution:

Step 1: Given inequality

31 < –5x + 6

Step 2: Subtract 6 from both sides of the inequality.

31 – 6 < –5x + 6 – 6

25 < –5x

Step 3: Multiply both sides by –1 to reverse the inequality.

25 × (–1) > –5x × (–1)

–25 > 5x

Step 4: Divide by 5 on both sides.

–5 > x

The correct answer is –5 > x.

Student's error is –5 < x.