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#26 2011-10-06 23:39:03
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Linear functions and Matrices
Hi;
No, a is what you never solve for. It is a coefficient,
2x+5y-(a+2)z=3
Look at that. The (a+2) is a coefficient just like the 2 and the 5. x,y, and z are variables, you solve for them.
Now we know that:
we just need z. How would you do that?
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#27 2011-10-06 23:51:35
- Marisca
- Member
- Registered: 2011-04-22
- Posts: 53
Re: Linear functions and Matrices
Just a wild guess, but would you sub the values of x and y into the first equation?
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#28 2011-10-06 23:53:41
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Linear functions and Matrices
Hi;
Do you mean this one?
If so, you are correct, do that now and let us get rid of this horrible problem.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#29 2011-10-06 23:59:51
- Marisca
- Member
- Registered: 2011-04-22
- Posts: 53
Re: Linear functions and Matrices
Alright I got
(2a-5)/(a-3)-z=2
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#30 2011-10-07 00:02:04
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Linear functions and Matrices
Correct! Now please get z by itself.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#31 2011-10-07 00:04:11
- Marisca
- Member
- Registered: 2011-04-22
- Posts: 53
Re: Linear functions and Matrices
Z=1/(a-3)
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#32 2011-10-07 00:06:22
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Linear functions and Matrices
Hi;
Just one more thing. It is not correct to interchange z and Z. Believe it or not they are not the same.
Mathematics is a language. Like any other it has rules and conventions to follow.
You did well.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#33 2011-10-07 00:09:35
- Marisca
- Member
- Registered: 2011-04-22
- Posts: 53
Re: Linear functions and Matrices
Thanks for the tip 
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#34 2011-10-07 00:11:53
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Linear functions and Matrices
Do you have enough? Do not worry about a problem such as this one. They are rare and just long and tedious.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#35 2011-10-07 00:16:50
- Marisca
- Member
- Registered: 2011-04-22
- Posts: 53
Re: Linear functions and Matrices
Yes I think so. It's probably not likely that they're going to sneak it into my exam.
Thanks for your help.
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#36 2011-10-07 00:22:46
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Linear functions and Matrices
Your welcome! Hope to see you again.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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#37 2011-10-08 06:25:09
- Hixy
- Member
- Registered: 2011-09-24
- Posts: 15
Re: Linear functions and Matrices
Hi
Just wanted to add another way of solving the problem with matrices which can make the problem quite simple. You can find it .
Hopefully that gave you a slightly different perspective on the problem.
Last edited by Hixy (2011-10-08 08:07:10)
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#38 2011-10-08 07:55:25
- bobbym
- bumpkin
- From: Bumpkinland
- Registered: 2009-04-12
- Posts: 109,606
Re: Linear functions and Matrices
Hi;
Yes, linear algebra is the right way to do it. The matrix could be inverted by Gaussian elimination, or the system solved by the clumsy Kramers rule. I think a groebner basis could also be used to eliminate an equation.
Two reasons why I did not suggest any of it to her:
1)I do not think she is ready for that.
2)In my opinion school problems are always set up to respond well to whatever method they are trying to illustrate. That is why I began substitution, confident that it would all work out.
In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.
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