# Thread: help with rearrange equation

1. ## help with rearrange equation

just want to ask which is correct way of doing ax + by + x = 0
example is y = 2x + 8

y -y = 2x -y + 8 (basically take away y both sides)
0 = 2x -y + 8

or

y - 2x -8 = 2x + 8 - 2x - 8 (instead of taking y away, take 2x + 8 away both sides)
-2x + y - 8 = 0

which one is correct?

2. ## Re: help with rearrange equation

Originally Posted by yuenj01
just want to ask which is correct way of doing ax + by + x = 0
example is y = 2x + 8

y -y = 2x -y + 8 (basically take away y both sides)
0 = 2x -y + 8

or

y - 2x -8 = 2x + 8 - 2x - 8 (instead of taking y away, take 2x + 8 away both sides)
-2x + y - 8 = 0

which one is correct?
The first option was surely far more straightforward? Although either method is correct.

3. ## Re: help with rearrange equation

Originally Posted by Quacky
The first option was surely far more straightforward? Although either method is correct.
that is what i was thinking. in da exams, is it acceptable?

4. ## Re: help with rearrange equation

If you multiply either solution by -1 on both sides, you'll find that they're exactly the same.

5. ## Re: help with rearrange equation

Originally Posted by yuenj01
just want to ask which is correct way of doing ax + by + x = 0
Do you mean $ax+by+c=0$?

Originally Posted by yuenj01
example is y = 2x + 8

y -y = 2x -y + 8 (basically take away y both sides)
0 = 2x -y + 8

or

y - 2x -8 = 2x + 8 - 2x - 8 (instead of taking y away, take 2x + 8 away both sides)
-2x + y - 8 = 0

which one is correct?