x + y = 12
y = 2x
2007-04-28 18:07:52 · 9 answers · asked by John Crow 1 in Science & Mathematics ➔ Mathematics
x+2x=12
3x=12
x=4
y=2*4
y=8, x=4
2007-04-28 18:11:59 · answer #1 · answered by jeevus_ud1991 1 · 0⤊ 0⤋
just substitute y=2x into the first equation:
this gives x+2x=12 or x=4 ; then put the # 4 in place of x in the secound equation ; y = 2(4) or y = 8
2007-04-29 01:20:04 · answer #2 · answered by lahomaokie 2 · 0⤊ 0⤋
x + y = 12
y = 2x now replace 2x instead of y in the first equation then 2x+x=12 so 3x=12 divide both sides to 3 we have x is 4, but y=2x so y=2x=(2)(3)=6
2007-04-29 01:33:36 · answer #3 · answered by Ahmad k 2 · 0⤊ 0⤋
x + y = 12 (1)
y = 2x (2)
sub (2) into (1)
x+(2x)=12
3x=12
x=4 (3)
sub (3) into (2)
y=8
therefore, (4,8) is the solution.
2007-04-29 02:02:45 · answer #4 · answered by Winnie 3 · 0⤊ 0⤋
plug into the first equation the answer from the second equation:
therefore, since y=2x,
x+(2x)=12,
and therefore 3x=12
x=4
but it's not over yet...
now plug in the answer for "x" (4) into the second equation..
y=2(4)=8
2007-04-29 01:15:23 · answer #5 · answered by Anonymous · 0⤊ 0⤋
x + 2x = 12
3x = 12
x = 4
y = 8
2007-04-29 08:20:50 · answer #6 · answered by Como 7 · 0⤊ 0⤋
since y=2x,
x+2x=12
and this shows that 3x=12, then x=4
and y =8
2007-04-29 01:11:19 · answer #7 · answered by Gman 2 · 1⤊ 0⤋
x + 2x = 12
3x = 12
x = 4
y = 2(4) = 8
ANS : (4,8)
2007-04-29 01:18:34 · answer #8 · answered by Sherman81 6 · 0⤊ 0⤋
x=12-y
y=2(12-y)
y=24-2y
3y=24
y=8
2007-04-29 01:10:34 · answer #9 · answered by Anonymous · 0⤊ 1⤋