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March 12th, 06:23 PM
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#1 (permalink)
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We The People
Join Date: Mar 2003
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Math Help (Pre-Calc)
x + y -5z = 3
x - 2z = 1
2x - y - z = 0
Solve using elimination.
If you try to eliminate y, you wind up with the same equation twice: 3x - 6z = 3
So I'm kind of stuck.
-Jin
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Originally Posted by Andrew Jackson
Gentlemen, I have had men watching you for a long time and I am convinced that you have used the funds of the bank to speculate in the breadstuffs of the country. When you won, you divided the profits amongst you, and when you lost, you charged it to the bank. You tell me that if I take the deposits from the bank and annul its charter, I shall ruin ten thousand families. That may be true, gentlemen, but that is your sin! Should I let you go on, you will ruin fifty thousand families, and that would be my sin! You are a den of vipers and thieves.
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March 12th, 06:27 PM
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#2 (permalink)
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Administrator
Join Date: Sep 2002
Location: On a very high horse
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3x-6z=3 is fine
then multiply the second equation by -3 to get -3x +6z = -3
add that to your 3x - 6z = 3 to get 0 = 0
That means that you have infinite solutions. So set one of your variables equal to "a", math teachers tell you to make it z. so if z=a, plug it in to your other equations, and get your x and y values in terms of a.
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March 12th, 06:37 PM
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#3 (permalink)
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ABCDEFGHIJKLMNOPQRSTFU
Join Date: May 2002
Location: Traverse City, MI
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I gave it a stab another way, too. I'm not sure it's solvable in the sense that you'll get numbers for x,y,z.
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March 12th, 06:47 PM
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#4 (permalink)
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Administrator
Join Date: Sep 2002
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Right, there are infinite solutions to it.
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March 12th, 06:48 PM
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#5 (permalink)
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We The People
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Are you supposed to make z equal to the equation 3x - 6z = 3?
So would it be like z = (1/2)x + -(1/2)?
And then would I just plug that in to z for the other equations and solve?
-Jin
__________________
Quote:
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Originally Posted by Andrew Jackson
Gentlemen, I have had men watching you for a long time and I am convinced that you have used the funds of the bank to speculate in the breadstuffs of the country. When you won, you divided the profits amongst you, and when you lost, you charged it to the bank. You tell me that if I take the deposits from the bank and annul its charter, I shall ruin ten thousand families. That may be true, gentlemen, but that is your sin! Should I let you go on, you will ruin fifty thousand families, and that would be my sin! You are a den of vipers and thieves.
|
Campaign For Liberty
The Declaration of Independence
U.S. Constitution
The Wealth of Nations
Common Sense
Give Me LIBERTY Or Give Me DEATH |
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March 12th, 06:49 PM
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#6 (permalink)
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ABCDEFGHIJKLMNOPQRSTFU
Join Date: May 2002
Location: Traverse City, MI
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Quote:
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Originally Posted by Jinjiro
Are you supposed to make z equal to the equation 3x - 6z = 3?
So would it be like z = (1/2)x + -(1/2)?
And then would I just plug that in to z for the other equations and solve?
-Jin
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Tried that...something like that. All I got was 3=3, 1=1, and 0  . All the variables subtract out. |
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March 12th, 06:51 PM
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#7 (permalink)
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We The People
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Yeah, that's what I got. I guess they're all infinite solutions? Or something...
-Jin
__________________
Quote:
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Originally Posted by Andrew Jackson
Gentlemen, I have had men watching you for a long time and I am convinced that you have used the funds of the bank to speculate in the breadstuffs of the country. When you won, you divided the profits amongst you, and when you lost, you charged it to the bank. You tell me that if I take the deposits from the bank and annul its charter, I shall ruin ten thousand families. That may be true, gentlemen, but that is your sin! Should I let you go on, you will ruin fifty thousand families, and that would be my sin! You are a den of vipers and thieves.
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Campaign For Liberty
The Declaration of Independence
U.S. Constitution
The Wealth of Nations
Common Sense
Give Me LIBERTY Or Give Me DEATH |
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March 12th, 07:01 PM
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#8 (permalink)
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I'm a big soft teddy bear
Join Date: Nov 2003
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use a matrix... i'll solve it later if you don't know how to do it that way.
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March 12th, 07:11 PM
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#9 (permalink)
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I'm a big soft teddy bear
Join Date: Nov 2003
Location: downingtown, pennsylvania
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[[1 1 -5] -1
[1 -2 0]
[2 -1 -1]]
then multiply by
[[3]
[1]
[0]]
the first matrix shown is multiplied by the inverse, because the original eq A (x,y,z)= B
then it goes to:
(x,y,z)=A^-1 * B
my calculator gave me {-1, -1, -1}
so perhaps infinate solutions is correct?
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March 12th, 07:13 PM
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#10 (permalink)
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shine on.
Join Date: Oct 2003
Location: panhandle
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Pre-calc? We did that this year in Algebra2H
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March 12th, 08:10 PM
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#11 (permalink)
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Senior Member
Join Date: May 2005
Posts: 1,743
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Quote:
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Originally Posted by big_balla89
Pre-calc? We did that this year in Algebra2H
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yea i was in Algebra 2 last year and we did the same stuff. this year in trig/precalc all we did was stuff with sin/cos/tan
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south georgia special
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March 12th, 08:25 PM
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#12 (permalink)
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shine on.
Join Date: Oct 2003
Location: panhandle
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Quote:
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Originally Posted by mynameisgeorgel
yea i was in Algebra 2 last year and we did the same stuff. this year in trig/precalc all we did was stuff with sin/cos/tan
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Trig...
We are doing that this year, too. We're dealing with sec, csc, and cot as well.
I don't like it because its in the morning and by the time I'm fully awake, he's through with the lesson and giving out the assignment... Bah.
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March 12th, 08:54 PM
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#13 (permalink)
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We The People
Join Date: Mar 2003
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Quote:
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Originally Posted by big_balla89
Pre-calc? We did that this year in Algebra2H
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It's supplementary with matrices, so you'll probably do it again. We did it in algebra as well.
-Jin
__________________
Quote:
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Originally Posted by Andrew Jackson
Gentlemen, I have had men watching you for a long time and I am convinced that you have used the funds of the bank to speculate in the breadstuffs of the country. When you won, you divided the profits amongst you, and when you lost, you charged it to the bank. You tell me that if I take the deposits from the bank and annul its charter, I shall ruin ten thousand families. That may be true, gentlemen, but that is your sin! Should I let you go on, you will ruin fifty thousand families, and that would be my sin! You are a den of vipers and thieves.
|
Campaign For Liberty
The Declaration of Independence
U.S. Constitution
The Wealth of Nations
Common Sense
Give Me LIBERTY Or Give Me DEATH |
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March 12th, 09:00 PM
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#14 (permalink)
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ABCDEFGHIJKLMNOPQRSTFU
Join Date: May 2002
Location: Traverse City, MI
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Yeah...we're doing linear algebra in Differential Equations.
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March 12th, 09:07 PM
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#15 (permalink)
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Senior Member
Join Date: May 2005
Posts: 1,743
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Quote:
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Originally Posted by big_balla89
Trig...
We are doing that this year, too. We're dealing with sec, csc, and cot as well.
I don't like it because its in the morning and by the time I'm fully awake, he's through with the lesson and giving out the assignment... Bah.
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yea i left those out sec csc cot
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south georgia special
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March 13th, 06:59 AM
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#16 (permalink)
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The Realest ***** Here.
Join Date: Mar 2005
Location: South Central Kentucky
Posts: 7,154
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Quote:
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Originally Posted by big_balla89
Pre-calc? We did that this year in Algebra2H
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same here... if it wasnt done solved i woulda gave it a shot...im still getting hang of it...we jus had a test over this last friday. |
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March 13th, 03:50 PM
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#17 (permalink)
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soccer, futbol.
Join Date: Dec 2004
Posts: 806
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When the equation is put into standard matrix form it becomes a singular matrix, meaning it's determinant is zero and also has no inverse...  and if i remember correctly, there are NO solutions because when you solve a matrix algebraically, such as we have to do in this case, you are in turn taking the inverse when you solve, (inverse operations), and you all know you can not divide by zero, which you have to do to solve this, so it has no REAL solution. |
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Math Help (Pre-Calc)
