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Coleycole69
Nov 29, 2005, 03:01 PM
Im in Algebra 3 and I need to make up this assignment so I need help on this problem:

y=3x
x+y=8
We have to graph and solve the system by substition
Please help me with this problem if u can!! :D

CaptainForest
Nov 29, 2005, 03:40 PM
y = 3x

x + y = 8 (which is the same thing as y = 8-x)

Therefore,.


8-x = 3x
8 = 4x
2 = x

y = 3x
y = 3(2)
y = 6

x + y = 8
(2) + (6) = 8

Therefore, x = 2 and y=6.

I don't remember how to graph it though.

Coleycole69
Nov 29, 2005, 03:44 PM
Thank You
I don't need help with the graphing
thanks Again :D

Now That was number one but now I need help with #8

2x=3y
x=3y-3

Again we have to solve it by substition and create a graph :)

CaptainForest
Nov 29, 2005, 03:57 PM
2x = 3y (same thing as x = 3y / 2)

and

x = 3y-3

Therefore,

3y/2 = 3y-3
3y = 2(3y-3)
3y=6y-6
6 = 3y
2 = y

x = 3y-3
x = 3(2) -3
x = 3

Therefore, x=3 and y=2

Coleycole69
Nov 29, 2005, 04:06 PM
Thanks for the help Captainforest
You Have helped me complete my Algebra Homework.
Thank u very much again :D

CaptainForest
Nov 29, 2005, 05:55 PM
Your welcome