#1
Alright, so I'm having some trouble solving this group of equations. I'm not going to go into detail on exactly how your supposed to do it, so whoever can help me hopefully knows. Anyway, I can't get the right answer for the soluton. When I tried solving it, I got:
x = 5
y = (-4)
z = (-4)
But when I plug those back into each equation, it doesn't work out, so i'm a bit stumped. Here's the equations:

x+y+z = 3
2x-3y+z = 9
4x-5y+2z = 16

Little help from anybody?
Thanks.
#3
^what he said.

If you haven't already got it, 2x-3y=z.

I don't feel like doing any more. I had today off school and I'm not going to occupy any of it with schoolwork.
#4
MATRICIES ARE YOUR FRIEND!!!! (sp?)

A V B
|1 1 1| |X| | 3 |
|2 3 1| X |Y| = | 9 | to solve for V you put A^-1 X B= V
|4 5 2| |Z| |16|

plug into calc. you get:

| 2 |
| 2 | which means X=2 Y=2 Z=-1
|-1 |

yes, i know im a genious, than you g'day.


EDIT: wow it got really messy when it took away all the extra spaces when i posted, ubt in short

X=2
Y=2
Z=-1

plug it in and check, i didnt.
Member #19 of the "Use Your Fucking Dictionary Club."

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#5
Quote by WyldeGibsonPlyr
(1) x+y+z = 3
(2) 2x-3y+z = 9
(3) 4x-5y+2z = 16

(1) z = 3 - y - x

(2) 2x - 3y + 3 - y - x = 9

x - 4y = 6

x = 6 + 4y

(3) 4(6 + 4y) - 5y + 2(3 - y - 6 - 4y) = 16

24 + 4y - 5y + 6 - 2y - 12 + 4y = 16

18 + y = 16

y = -2

x = 6 + 4(-2)

x = -2

z = 3 - y - x

z = 3 - (-2) - (-2)

z = 7


ed: Good job, "matrix man"
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#6
Quote by jammoe
(1) z = 3 - y - x

(2) 2x - 3y + 3 - y - x = 9

x - 4y = 6

x = 6 + 4y

(3) 4(6 + 4y) - 5y + 2(3 - y - 6 - 4y) = 16

24 + 4y - 5y + 6 - 2y - 12 + 4y = 16

18 + y = 16

y = -2

x = 6 + 4(-2)

x = -2

z = 3 - y - x

z = 3 - (-2) - (-2)

z = 7


ed: Good job, "matrix man"



Matricies are easier and not so............. brain hurt-y.
Member #19 of the "Use Your Fucking Dictionary Club."

Quote by chaoticmayhem
Toads are cool; it's those frog bastards that I don't like.


Whats your philosophy on life?
its so good to be back!
#7
the music man just got his ass kicked...jammoe is correct
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#8
Quote by pavel
the music man just got his ass kicked...jammoe is correct


what, no i didnt.
plug it in and check.

X= 2
Y= 2
Z= -1
Member #19 of the "Use Your Fucking Dictionary Club."

Quote by chaoticmayhem
Toads are cool; it's those frog bastards that I don't like.


Whats your philosophy on life?
its so good to be back!
#9
Well I could use a calculator to solve it and give you the answers..but i will do it by hand anyway.



That should be the right answer. If it isn't, then I have phailed at life because I can't even do high school maths properly.


EDIT: Indeed I do phail at life, my calculator gives me a different answer..and the calculator is quite often correct. I probably made a minor mistake somewhere. No one point it out, spare me the embarassment.
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#11
Quote by The*Music*Man
Dood Im Right Plug It In!


no, you're not. thats a minus 5y in the last equation not plus 5y.....
...Nothing you've ever...
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#12
Ohhh!!!!

damnit


sorry guys, simple mistake.


Edit: the martix thing still works.........but...........i dont want to plug it in my calc. again, i think the other guys right.
Member #19 of the "Use Your Fucking Dictionary Club."

Quote by chaoticmayhem
Toads are cool; it's those frog bastards that I don't like.


Whats your philosophy on life?
its so good to be back!
#13
x=-2
y=-2
z=7
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#14
I'll teach you how to use Reduced Row Echelon form and solve it in a couple of minutes.
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#15
Echelon form is really confusing to me.
Member #19 of the "Use Your Fucking Dictionary Club."

Quote by chaoticmayhem
Toads are cool; it's those frog bastards that I don't like.


Whats your philosophy on life?
its so good to be back!