Question

Eduardo solved the following inequality, and his work is shown below:

-5 (x+4) + 21 > -3 + 4(x-8)
-5x - 20 + 21 > -3 + 4x - 32
-5x + 1 > 4x -35
-9x > -36
x>4

What mistake did Eduardo make in solving the inequality?

A. When dividing by -9, he did not change the > to <

B. He subtracted 4x from both sides when he should have added 5x

C. He subtracted 1 from both sides when he should have added 36

D. He did not make a mistake

Answer 1

When you multiply or divide an inequality by a negative number, you need to change the direction of the inequality sign.