For each of the following pairs of equations, find the point of intersection by adding the two equations together. Remember: you might need to change the coeffients and/or signs of the variables before adding.
Help!
x-y = -1
x+y= 9
For each of the following pairs of equations, find the point of intersection by adding the two equations together. Remember: you might need to change the coeffients and/or signs of the variables before adding.
Help!
x-y = -1
x+y= 9
If you add two equations, you are their left hand sides together, and their right hand sides together.
So you'd get:
$\displaystyle x-y + (x+y) = -1+9 $
$\displaystyle x-y+x+y = 8 $
$\displaystyle 2x = 8 $
$\displaystyle x = 4 $
Then just put x = 4 into one of the original equations to get y!
$\displaystyle x + y = 9 $
$\displaystyle 4+y = 9 $
$\displaystyle y = 9-4$
$\displaystyle y = 5 $
Okay? What I don't understand is how you got the -1 and why you have the x - y (x+y)... I don't understand what the reasoning is behind that. Could you explain that to me?
Thanks so much for helping me... I AM getting the same answer but not really understanding the way I'm getting it.. make sense? LOL
Thanks again!!!