# simultaneous equations

Discussion in 'Math' started by amilton542, Feb 22, 2011.

1. ### amilton542 Thread Starter Active Member

Nov 13, 2010
494
64
i dont have great difficulty in rearranging simultaneous equations with an x and y value equals a number but when a third value is put in things confuse me : im trying to rearrange this formula

y = 8 - 2x
x + y + 7 = 0

ive rearranged the top one to y + 2x = 8

the second one i dont no what to do with the zero ? my attempt is x + y = 0 - 7

2. ### Georacer Moderator

Nov 25, 2009
5,142
1,266
Quite right. Can you solve the system now?

3. ### amilton542 Thread Starter Active Member

Nov 13, 2010
494
64
maths guru is that a yes your answer is right ( keep all cons together) then i can solve the "system"

4. ### Georacer Moderator

Nov 25, 2009
5,142
1,266
Yes, I said that your assumption about putting the '7' on the right hand expression was correct. Your new system should be:

$\left\ \begin{array}{l} y+2x=8 \\ x+y=-7\\
\end{array} \right}$

Can you handle that system? Do you need any more help?

Last edited: Feb 22, 2011
5. ### amilton542 Thread Starter Active Member

Nov 13, 2010
494
64
just what i was looking for