Question

Verifying Work
Jason solved the following equation to find the value for x.

–8.5x – 3.5x = –78

x = 6.5

Describe how Jason can check his answer.

Answer 1

To check, Jason should substitute x = 6.5 into the original equation and verify both sides match.

Substitute:
–8.5(6.5) – 3.5(6.5)

Factor out 6.5:
(–8.5 – 3.5)·6.5 = (–12)·6.5 = –78

Or compute separately:
–8.5·6.5 = –55.25 and –3.5·6.5 = –22.75, so –55.25 – 22.75 = –78.

Because the left side equals the right side (–78), the answer x = 6.5 is correct.