SOLUTION: I really need some help on substitution methods I have tried all the problems. I understood a the beginning, but then it got harder. The problem is y/2-x=1 and x+y+7=0.

Algebra ->  Coordinate Systems and Linear Equations  -> Lessons  -> Linear Equations Lesson -> SOLUTION: I really need some help on substitution methods I have tried all the problems. I understood a the beginning, but then it got harder. The problem is y/2-x=1 and x+y+7=0.      Log On


   

Question 77823This question is from textbook Algebra
: I really need some help on substitution methods I have tried all the problems. I understood a the beginning, but then it got harder. The problem is y/2-x=1 and x+y+7=0. This question is from textbook Algebra

Answer by Earlsdon(6294) About Me  (Show Source):
You can put this solution on YOUR website!
Solve by substitution:
y%2F2+-+x+=+1 Solve this one for x: highlight%28x+=+y%2F2+-+1%29 and substitute for x in the second equation.
x%2By%2B7+=+0
%28y%2F2+-+1%29%2By%2B7+=+0 Simplify by multiplying by 2 to clear the fraction.
y-2%2B2y%2B14+=+0 Combine like-terms.
3y%2B12+=+0 Subtract 12 from both sides.
3y+=+-12 Finally, divide both sides by 3.
y+=+-4
Now substitute this value of y into the highlighted equation above to find x.
x+=+%28-4%29%2F2+-+1
x+=+-2-1
x+=+-3
The solution is: (-3, -4)
Here's the graphic solution:
graph%28300%2C200%2C-5%2C5%2C-8%2C5%2C2x%2B2%2C-x-7%29