solve the following system of equations
x-2y=5
-3x+2y=7
2006-09-08 15:51:35 · 9 answers · asked by Anonymous in Education & Reference ➔ Homework Help
x-2y=5
-3x+2y=7
Multiply the first one by 3:
3x-6y=15
-3x+2y=7
The 3x and -3x cancel out:
-6y=15
2y=7
Now, combine the equations:
-4y=22
Divide each side by negative 4:
y= -5.5
Now, plug that into one of the original equations:
3x-6y=15
3x-6(-5.5)=15
3x+33=15
Subtract the 33 from both sides:
3x= -18
Divide both sides by 3:
x= -6
Now, check with the other original equation:
-3x+2y=7
-3(-6)+2(-5.5)=7
18+ (-11) =7
7=7
ANSWERS
x= -6
y= -5.5
2006-09-08 15:54:40 · answer #1 · answered by Anonymous · 0⤊ 0⤋
This seems simple enough. First take one of the equations and solve for one of the variables. Such as:
x = 5 + 2y or y = (5 - x)/2
next plug one of these equations into the second equation and solve for the variable. Like this:
-3(5+2y) + 2y = 7
-15 -6y +2y = 7
-4y = 22
y = -5.5
now that you know what y is you can solve for x. Then plug each value for x and y into each equation to check if your right.
x-2(-5.5) = 5
x = -6
Check:
-6 - [2(-5.5)] = 5....true
-3(-6) +2(-5.5) = 7....true
2006-09-08 23:15:20 · answer #2 · answered by Anonymous · 1⤊ 0⤋
x-2y=5
isolate x: x=5+2y
plug x into the 2nd equation
-3(5+2y)+2y = 7
solve y
-15-6y+2y = 7
-15-4y=7
y=-(7+15)/4
y=-22/4
plug y=-22/4 into first equation and solve for x
x-2(-22/4)=5
x+(44/4) = 5
x=5-11
x = -6
in short, x = -6 and y = -22/4
check your work.....
plug the solved x and y into the second equation....
(-6) - 2(-22/4) = 5 ??
-6+(44/4) = 5
-6 + 11 = 5 YES...
Q.E.D.
2006-09-08 23:01:30 · answer #3 · answered by MJV 2 · 0⤊ 0⤋
solve the top for x. then use substitution and plug the x value into the second equation to find y. after finding y plug the value into origional equation to find x
x-2y=5
-3x+2y=7
x=2y+5
-3x+2y=7
-3(2y+5)+2y=7
-6y-15+2y=7
-4y=22
y=-5.5
plug y into first equation
x-2(-5.5)=5
x+11=5
x=-6
(-6,-5.5)
2006-09-08 22:54:34 · answer #4 · answered by Azary1010 3 · 0⤊ 1⤋
X=6, Y=1/2(0.5)
x-2y=5
(6)-2y=5
x-2y=5 -2y=-1
-3x+2y=7 --- ----
------------------- -2 -2
-2x=12 y=1/2 (0.5)
---- ----
-2 -2
x=6
2006-09-08 23:10:49 · answer #5 · answered by hopeless 4 · 0⤊ 0⤋
We're not going to do your homework for you, man.
Oh, wait, this IS homework help! Nevermind.
2006-09-08 22:57:13 · answer #6 · answered by eight_foot_bunch 3 · 1⤊ 0⤋
Dude, I hated math in high school!!
2006-09-08 22:53:14 · answer #7 · answered by Tiffany 4 · 1⤊ 0⤋
HAHAHAHAAA, you should have paid attention in class! You are on your own bud.
2006-09-08 22:55:17 · answer #8 · answered by **KELLEY** 6 · 0⤊ 0⤋
why don't you do your own homework
2006-09-08 22:57:22 · answer #9 · answered by Anthony M 2 · 0⤊ 0⤋