Question

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

−4(x + 8) + 25 ≤ −2 + 1(x − 50)
−4x − 32 + 25 ≤ −2 + 1x − 50
−4x − 7 ≤ 1x − 52
−5x ≤ −45
x ≤ 9
What mistake did Andrew make in solving the inequality? (2 points)


He subtracted 1x from both sides when he should have added 4x.

When dividing by −5, he did not change the ≤ to ≥.

He added 7 to both sides when he should have added 52.

He did not make a mistake.

Answer 1

When dividing by - 5 he did not change ≤ to ≥

His calculations are correct down to the line - 5x ≤ 9

When dividing or multiplying by a negative quantity the inequality symbol must be reversed, thus

- 5x ≤ 9 ( divide both sides by - 5 )

x ≥ 9 ← inequality symbol reversed

Answer 2

Try this option:

rule: if to make a dividing by negative number (<0), the inequatlity sign must be changed to opposite.

According the rule described above, the correct answer is

'When dividing by -5, he did not change the ≤ to ≥'.