SOLUTION: Solve each system by addition. a) x + y = 7 x - y = 9 b) x - 2y = -1 -x + 5y = 4 c) 3x + 5y = -11 x - 2y = 11 d) 2x = 2-y 3x + y = -1

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: Solve each system by addition. a) x + y = 7 x - y = 9 b) x - 2y = -1 -x + 5y = 4 c) 3x + 5y = -11 x - 2y = 11 d) 2x = 2-y 3x + y = -1       Log On


   

Question 351021: Solve each system by addition.
a)
x + y = 7
x - y = 9
b)
x - 2y = -1
-x + 5y = 4
c)
3x + 5y = -11
x - 2y = 11
d)
2x = 2-y
3x + y = -1


Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
a) Add the equations,
x%2By%2Bx-y=7%2B9
2x=16
highlight%28+x=8%29
Then from the first equation,
8%2By=7
highlight%28y=-1%29
.
.
.
b)Add the equations,
x+-+2y+-x+%2B+5y+=+-1%2B4
3y=3
highlight%28y=1%29
Then from the first equation,
x-2=-1
highlight%28+x=1%29
.
.
.
c)
1.3x+%2B+5y+=+-11
2.x+-+2y+=+11+
Multiply eq. 2 by (-3) and add the equations together,
3x%2B5y-3x%2B6y=-11-33
11y=-44
highlight%28y=-4%29
Then from eq. 2,
x%2B8=11
highlight%28x=3%29
.
.
.
d) Rearrange the first equation, then subtract the first from the second,
2x+=+2-y
.
.
.
2x%2By=2
3x+%2B+y+=+-1+
.
.
3x%2By-2x-y=-1-2
highlight%28x=-3%29
Then from the first equation,
-6%2By=2
highlight%28y=8%29