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 littlebu December 6th, 2010 02:52 PM

Help with Matrix problem

I do not now how to do these types of problems. Could somebody point me in the right direction?

Find the matrix A such that

A[ 1 0 ] = [ -5 -4]
[ -1 4] = [ 7 12]

hint: let A = [a b]
[c d]

 The Chaz December 6th, 2010 03:20 PM

Re: Help with Matrix problem

Do you know how to do matrix multiplication?

Set this equal to the given matrix,

then solve by setting corresponding elements equal to each other.

 littlebu December 6th, 2010 03:33 PM

Re: Help with Matrix problem

Quote:
 Originally Posted by The Chaz Do you know how to do matrix multiplication? Set this equal to the given matrix, then solve by setting corresponding elements equal to each other.

I get to here:

Then:

In equation form is

a = -5 b= -4
-a + 4c = 7 -b +4d = 12

Solving for c and d gives

a = -5 b = -4
c = .5 d = d = 2

Is this correct?

I am new to this, just trying to figure it out by following along in a book.

 greg1313 December 6th, 2010 03:51 PM

Re: Help with Matrix problem

4b = -4
a - b = -5
4d = 12
c - d = 7

 The Chaz December 6th, 2010 04:10 PM

Re: Help with Matrix problem

Quote:
 Originally Posted by littlebu ...I am new to this, just trying to figure it out by following along in a book.
You should follow along with my reply!
Compare the matrices in my reply with the statements in greg1313's post

 soroban December 6th, 2010 04:11 PM

Re: Help with Matrix problem

Hello, littlebu!

It would help if you didn't scatter your work . . .

Quote:

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 littlebu December 6th, 2010 05:13 PM

Re: Help with Matrix problem

Thanks for the replies everyone, this is really helpful and makes sense now. This forum is fantastic, it is hard to "teach" yourself from a book when you don't know what to do, thanks again for the help I have a feeling I am going to be asking a lot of questions here. Hope you all don't get annoyed with me lol.

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