You are substituting for y instead of x
Besides that you were still keeping the y as well.
5(3-2y) + 4y = 8
15 - 10y + 4y = 8
-6y = -7
y = 7/6
then in x = 3-2y
x = 3-14/6 = 2/3
x = 2/3 , y = 7/6
x+2y=3
5x+4y=8
I isolated x+2y=3 to make: x=3-2y
then i began to sub in equation one with equation two:
5x+4y(3-2y)=8
5x+12-8y=8
after that i began to try to solve the equation but my answers were not correct. any help would be greatly appreciated!
4 answers
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
x-y= 3
i isolated the second equation into y=3+x
so: 6x+5y(3+x)=7
6x+15+5x=7
6x+5x-15+15=7+15
11/11= 22/11
x=2
then i subbed in the other equation..
6(2)+5y=7
12+5=7-12
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.
for example this one:
6x+5y= 7
x-y= 3
i isolated the second equation into y=3+x
so: 6x+5y(3+x)=7
6x+15+5x=7
6x+5x-15+15=7+15
11/11= 22/11
x=2
then i subbed in the other equation..
6(2)+5y=7
12+5=7-12
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.
Horizontal line through(5,0)
-2(2y+15)<-6y-14