Question

4. Explain and correct the error made by a student who simplified this expression.

–2x – 4x + 8y – y
(–2 – 4)x + (8 – 0)y
–6x + 8y

Answer 1

I notice that the first equation has a 7x, term and the second equation has a -7x term. These terms will cancel if we add the equations together—that is, we'll eliminate the the x terms:

Explanation:

2y+7x= -5 + 5y-7x=12