Dividing and signs
The question
Noor wrote 3(x + 7) − (x − 9) = 2x + 30. Which is correct?
Noor wrote 3(x + 7) − (x − 9) = 2x + 30. Which is correct?
3(x + 7) − (x − 9)
3(x + 7) − (x − 9)=3x + 21 − x + 9
3(x + 7) − (x − 9)=3x + 21 − x + 9
3(x + 7) − (x − 9)=2x + 30
3(x + 7) − (x − 9)=2x + 30
they wrote:2x + 30
- Do the step yourself first, then compare with their line.
- On your own, writing every step: 3(x + 7) − (x − 9) becomes 3x + 21 − x + 9.
- Tidy that up and it is 2x + 30.
- Now compare — this time the two agree, so their line is right.
How it works.
- 01
Do the step yourself first, then compare with their line.
- 02
On your own, writing every step: 3(x + 7) − (x − 9) becomes 3x + 21 − x + 9.
- 03
Tidy that up and it is 2x + 30.
- 04
Now compare — this time the two agree, so their line is right.