Solving Systems of Equations by Elimination
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Solving Systems of Equations by Elimination
Guest on Thu Jan 19, 2012 9:07 pm
3) x − y = 11
2x + y = 19
6) 8x + y = −16
−3x + y = −5
10) −4x + 9y = 9
x − 3y = −6
12) −7x + y = −19
−2x + 3y = −19
2x + y = 19
6) 8x + y = −16
−3x + y = −5
10) −4x + 9y = 9
x − 3y = −6
12) −7x + y = −19
−2x + 3y = −19
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Re: Solving Systems of Equations by Elimination
Your-Guardian-Angel on Thu Jan 26, 2012 1:37 pm
Using elimination you simply subtract the bottom equation from the top.
3) x-y=11
2x+y=19
For that problem you would do
x-y=11
-(2x+y=19)
-x-2y=-8
I put the original part in parenthesis to show that it's not -2x, but everything is subtracted from the x-y=11.
How I got my answer:
x-2x=-x, -y-y=-2y, 11-19=-8.
6) 8x+y=-16
-3x+y=-5
8x+y=-16
-(-3x+y=-5)
11x=-11
x=-1
How I Got My Answer:
8x-(-3x)=11x. y-y=0, so y is cancelled out of the equation. -16-(-5)=-11. 11x=-11. Divide both sides of the equation by 11 and you get x=-1.
Try the last two on your own.
10) -4x+9y=9
x-3y=-6
-4x+9y=9
-(x-3y=-6)
12) -7x+y=-19
-2x+3y=-19
-7x+y=-19
-(-2x+3y=-19)
3) x-y=11
2x+y=19
For that problem you would do
x-y=11
-(2x+y=19)
-x-2y=-8
I put the original part in parenthesis to show that it's not -2x, but everything is subtracted from the x-y=11.
How I got my answer:
x-2x=-x, -y-y=-2y, 11-19=-8.
6) 8x+y=-16
-3x+y=-5
8x+y=-16
-(-3x+y=-5)
11x=-11
x=-1
How I Got My Answer:
8x-(-3x)=11x. y-y=0, so y is cancelled out of the equation. -16-(-5)=-11. 11x=-11. Divide both sides of the equation by 11 and you get x=-1.
Try the last two on your own.
10) -4x+9y=9
x-3y=-6
-4x+9y=9
-(x-3y=-6)
- Spoiler:
- -5x+12y=15
12) -7x+y=-19
-2x+3y=-19
-7x+y=-19
-(-2x+3y=-19)
- Spoiler:
- -5x-2y=0
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Re: Solving Systems of Equations by Elimination
Your-Guardian-Angel on Sat Feb 04, 2012 7:41 pm
What are you confused about? Sorry, I was trying to make it less complicated :P
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Re: Solving Systems of Equations by Elimination
JENOVA's SOLDIER on Sat Feb 04, 2012 8:17 pm
If you don't mind my helping. I see the problem... This is rather easy math here... I'll take 6 there as an example.
6) 8x + y = −16
−3x + y = −5
So you want to arrange it as a subtraction equation as Guard did right? So it would be:
-3x+y=-5
-(8x+y=-16)
________
You'll notice that subtracting the bottom y with the top y gets rid of them. The leaves you with:
-11x=11 which means
x=-1
Then you take what you get for x and put it into the original equations, for example, putting it back into the first equation would look like:
8x + y = −16
8(-1)+y=-16
-8+y=-16
y=-16+8
y=-8
Though to be honest... it has been some... 4 or 5 years since I've had to do this math... So I'm not sure... But you should try subbing the x value that I found into the other equation... You should get the same thing I got for the one that I just tried above. You should get y=-8, I checked it, but you try it.
6) 8x + y = −16
−3x + y = −5
So you want to arrange it as a subtraction equation as Guard did right? So it would be:
-3x+y=-5
-(8x+y=-16)
________
You'll notice that subtracting the bottom y with the top y gets rid of them. The leaves you with:
-11x=11 which means
x=-1
Then you take what you get for x and put it into the original equations, for example, putting it back into the first equation would look like:
8x + y = −16
8(-1)+y=-16
-8+y=-16
y=-16+8
y=-8
Though to be honest... it has been some... 4 or 5 years since I've had to do this math... So I'm not sure... But you should try subbing the x value that I found into the other equation... You should get the same thing I got for the one that I just tried above. You should get y=-8, I checked it, but you try it.
Last edited by JENOVA's SOLDIER on Sat Feb 04, 2012 8:32 pm; edited 1 time in total
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Re: Solving Systems of Equations by Elimination
Wolves-Rule1 on Sat Feb 04, 2012 8:27 pm
I'm not even this far into math yet. So I have no clue. Lol
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Re: Solving Systems of Equations by Elimination
JENOVA's SOLDIER on Sat Feb 04, 2012 8:29 pm
I was right except for my last bit of math. Sorry, I'll go fix it.
Edit: There all better. I messed up the signs and screwed myself up lol. It happens to everyone
Edit: There all better. I messed up the signs and screwed myself up lol. It happens to everyone
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Re: Solving Systems of Equations by Elimination
Guest on Wed Feb 15, 2012 6:19 pm
what do with fraction like if x or y your fraction
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