Question

Find the student’s error in solving the following inequality.

2 < –3x –4 < 5
6 < –3x < 5
–2 > x > –5/3

Answer 1

The student didn't add 4 to all expressions in the inequality.
It should be:

`2<-3x-4<5 \ \ \ |+4 \\ 6<-3x<9 \ \ \ |/ (-3) \\ -2>x>-3`