y=-4y
3x+2y=20
2007-11-01 06:40:42 · 7 answers · asked by butterflt 1 in Science & Mathematics ➔ Mathematics
If x = -4y........................Eq 1
and
3x + 2y = 20..................Eq 2
Substitute from Eq1 the value of x ( -4y) into Eq 2
Therefore
-12y + 2y = 20
- 10y = 20
y = -2
Hope this helps :-)
2007-11-01 06:49:22 · answer #1 · answered by Rod Mac 5 · 0⤊ 0⤋
where the Y is in the second equation, put -4y
it would read:
3x+2(4)=20
3x+8=20
-8 -8
3x = 12
---- -----
3 3
x = 4
now instead of it being the Y...now in this equation substitute X.
***Note*** Use the ORIGNAL problem not the one you just solved.
it should read:
3(4)+2y=20
12+2y=20
-12 -12
2y = 8
--- ---
2 2
y = 4
your ordered pair should be (4, 4)
2007-11-01 13:53:30 · answer #2 · answered by Haley Mae 2 · 0⤊ 0⤋
There is only one value of y that makes the first equation work.
For the second equation, replace the y with the value you just found, then solve for x.
2007-11-01 13:44:54 · answer #3 · answered by DWRead 7 · 0⤊ 0⤋
i got x = 9 1/3
2007-11-01 13:44:40 · answer #4 · answered by ? 4 · 0⤊ 0⤋
Is it y = - 4x?
3x - 8x = 20
- 5x = 20
x = - 4
y = 16
2007-11-01 14:27:28 · answer #5 · answered by Como 7 · 0⤊ 0⤋
Wow i stayed home today so that i wouldn't have to use my brain but where ever i go maths engulfs me!
2007-11-01 13:47:41 · answer #6 · answered by Crazilicous 3 · 0⤊ 0⤋
hey check your question again...
2007-11-01 13:47:51 · answer #7 · answered by warlock 2 · 0⤊ 0⤋