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

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

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

A. when dividing by -9, he did not change the inequality sign