2007-07-01 22:23:08 · 4 answers · asked by wilbert c 1 in Science & Mathematics ➔ Mathematics
y+x=7 ........ y+x =7..........(1)
x-3y=5 ........-3y+x=5..........(2)
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(1)-(2):
y-(-3y)+(x-x)=7-5
4y =2
/4 /4
4y/4 =2/4
y=2/4=1/2=0.5
(1): 0.5+x=7
x=7-0.5=6.5
2007-07-01 22:38:00 · answer #1 · answered by Arfianto M 2 · 1⤊ 0⤋
y+x=7
x-3y=5
subtract
4y=2
y=1/2
=> x=6 1/2
2007-07-02 05:39:16 · answer #2 · answered by harry m 6 · 0⤊ 0⤋
3x + 3y = 21
x - 3y = 5-----ADD
4x + 26
x = 26/4 = 13/2
y = 7 - 13/2
y = 1/2
Soln: x = 13/2 , y = 1/2
2007-07-06 02:42:12 · answer #3 · answered by Como 7 · 0⤊ 0⤋
y + x = 7
x - 3y = 5
Because both equations have an x on the same side, we can subtract:
x + y = 7
x - 3y = 5
-________
4y = 2
y = 0.5
So put y = 0.5 into the first equation (y + x = 7):
0.5 + x = 7
x = 6.5
y = 0.5
2007-07-02 06:11:44 · answer #4 · answered by 就是我 2 · 0⤊ 0⤋