SOLUTION: 2x-4y=6 2x+y=1 my teacher said to solve this by using substitution but i keep getting the worng answer, help plz :)!

Algebra ->  College  -> Linear Algebra -> SOLUTION: 2x-4y=6 2x+y=1 my teacher said to solve this by using substitution but i keep getting the worng answer, help plz :)!      Log On


   

Question 258778: 2x-4y=6
2x+y=1

my teacher said to solve this by using substitution but i keep getting the worng answer, help plz :)!
Found 2 solutions by Fombitz, richwmiller:
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
1.2x-4y=6
2.2x%2By=1+
Since both have a "2x" term solve eq. 1 for 2x and substitute into eq. 2,
1.2x-4y=6
2x=4y%2B6
.
.
.
2.2x%2By=1+
%284y%2B6%29%2By=1+
5y%2B6=1+
5y=-5+
y=-1
Then from above,
2x=4y%2B6
2x=4%28-1%29%2B6
2x=-4%2B6
2x=2
x=1
.
.
.
(x,y)=(1,-1)

Answer by richwmiller(17219) About Me  (Show Source):
You can put this solution on YOUR website!
So what did you try?
What did you get?

2x-4y=6
2x+y=1
Substitution might be the harder way to solve this
Elimination would be
Subtract the two and get
-5y=5
y=-1
2x-1=1
2x=2
x=1
However we will do it by substitution.
Solve the second for y
y=1-2x
Substitute 1-2x for y in the first
2x-4(1-2x)=6
2x-4+8x=6
10x =10
x=1
y=1-2(1)
y=1-2
y=-1
Same answers