Solve the system by addition. 2x – 4y = 7 4x + 2y = 9
2007-12-31 14:44:02 · 8 answers · asked by cutter1890 1 in Science & Mathematics ➔ Mathematics
2x - 4y = 7
8x + 4y = 18---------ADD
10x = 25
x = 5/2
10 + 2y = 9
2y = - 1
y = - 1/2
x = 5/2 , y = - 1/2
2007-12-31 21:31:14 · answer #1 · answered by Como 7 · 1⤊ 0⤋
x=4 and y=2
2016-05-28 08:00:37 · answer #2 · answered by raguel 3 · 0⤊ 0⤋
2x – 4y = 7 ........[1]
4x + 2y = 9 ........[2]
[2] * 2
8x + 4y = 18 .......[3]
[1] + [3]
10x = 25
x = 5/2
substitute x with 5/2 in [2]
4 * (5/2) + 2y = 9
10 + 2y = 9
2y = -1
y = -1/2
2008-01-04 12:16:43 · answer #3 · answered by ^ ³ 5 · 0⤊ 0⤋
easy combine like terms and you will come up with -6y=72x=9.
2007-12-31 14:55:09 · answer #4 · answered by Anonymous · 0⤊ 0⤋
the easiest way is by putting them on top of each other
2x - 4y = 7
4x + 2y = 9
now you need to get one variable to cancel out... the easiest would be the y's. so multiply the bottom equation by 2
2x - 4y = 7
8x + 4y = 18
now solve...
10x = 25
x = 2.5
fill that in either equation and solve for your y now
2(2.5) - 4y = 7
5 - 4y = 7
-4y = 2
y = - 1/2, or if you want them both decimale, - 0.5
2007-12-31 14:53:39 · answer #5 · answered by Shay 3 · 0⤊ 0⤋
4x -8y = 14 (multiply by 2)
4x + 2y = 9
____________(subtract)
-10y = 5
y = -1/2
4x + 2*-1/2 = 9
4x = 9 +1
x = 10/4 = 5/2
2007-12-31 14:52:41 · answer #6 · answered by Synchronizers 3 · 0⤊ 0⤋
4x-8y=14
substract
-10y=5
y=-1/2
x=5/2
2007-12-31 14:49:42 · answer #7 · answered by someone else 7 · 0⤊ 0⤋
2x – 4y = 7 ........[1]
4x + 2y = 9 ........[2]
[1] + 2*[2]
We get 10x = 25
x = 5/2
[1]: 2* 5/2 -4y = 7
y = -1/2
2008-01-04 14:33:16 · answer #8 · answered by SamC 5 · 0⤊ 0⤋