View Full Version : I have two Algebra 1 Equations that are Hard for me
Fred504610
Apr 12, 2009, 07:33 PM
they are
x+y=4
x-y=8
and
2x+y=1
x=2y+8
help me this is very hard for me :confused:
KISS
Apr 12, 2009, 07:40 PM
The first is easy; just add them and get 2x=12;
From there it's easy to find x & y. Do you understand what I did?
2nd;
multiply the bottom by -2
2x+y=1
-2x-4y=-16
add
-3y=-15; take it from there?
Fred504610
Apr 12, 2009, 07:44 PM
The first is easy; just add them and get 2x=12;
From there it's easy to find x & y. Do you understand what I did?
2nd;
multiply the bottom by -2
2x+y=1
-2x-4y=-16
add
-3y=-15; take it from there?
Thank you :)
ISneezeFunny
Apr 12, 2009, 07:45 PM
x+y=4
x-y=8
first equation:
x + y = 4
x = 4 - y
plug it into second equation.
x - y = 8
(4 - y) - y = 8
4 - 2y = 8
-2y = 4
y = -2
now, plug y back into the first equation.
x+y=4
x + (-2) = 4
x - 2 = 4
x = 6
you can solve the next problem this way as well.
Oconomowoc
Nov 18, 2010, 04:51 PM
x+y=4
x-y=8
x+y=4
x-x+y=4-x
y=4-x
x-(4-x)=8
x-4+x=8
2x-4=8
2x-4+4=8+4
2x=12
2x/2=12/2
x=6
x-y=4
6+y=4
6-6+y=4-6
y=-2
answer
x+y=4 x=6,y=-2
6+-2=4
6-2=4
4=4
correct!