Posted by peyton on Saturday, September 24, 2011 at 5:19pm.
x+2y=3
5x+4y=8
I isolated x+2y=3 to make: x=32y
then i began to sub in equation one with equation two:
5x+4y(32y)=8
5x+128y=8
after that i began to try to solve the equation but my answers were not correct. any help would be greatly appreciated!

Grade 10Math  Reiny, Saturday, September 24, 2011 at 6:20pm
You are substituting for y instead of x
Besides that you were still keeping the y as well.
5(32y) + 4y = 8
15  10y + 4y = 8
6y = 7
y = 7/6
then in x = 32y
x = 314/6 = 2/3
x = 2/3 , y = 7/6

Grade 10Math  peyton, Sunday, September 25, 2011 at 3:55pm
i understand how you got the answer i just don't get why i don't put 5x+4y before the equation because i have been for all the other ones and i got those ones right..
for example this one:
6x+5y= 7
xy= 3
i isolated the second equation into y=3+x
so: 6x+5y(3+x)=7
6x+15+5x=7
6x+5x15+15=7+15
11/11= 22/11
x=2
then i subbed in the other equation..
6(2)+5y=7
12+5=712
5y/5= 5/5
y= 1
and i checked my answer and it was correct.
i just don't understand what i'm doing wrong for the equation.. because i keep thinking the full equation must go first not separate it.

Grade 10Math  Penny, Monday, September 26, 2011 at 1:59pm
Horizontal line through(5,0)

Grade 10Math  Anonymous, Tuesday, April 30, 2013 at 4:58pm
2(2y+15)<6y14
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