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Evaluate: \(\left[\begin{matrix}1 & 2 &1 & 3 \\2&3&2&0\\3&1&0&1\\0&0&3&2\end{matrix}\right]\)
 one year ago
 one year ago
Evaluate: \(\left[\begin{matrix}1 & 2 &1 & 3 \\2&3&2&0\\3&1&0&1\\0&0&3&2\end{matrix}\right]\)
 one year ago
 one year ago

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CalcmathleteBest ResponseYou've already chosen the best response.0
I got 102. Is it correct or did I get an arithmetic error somewhere?
 one year ago

CalcmathleteBest ResponseYou've already chosen the best response.0
Hmm... Let me just double check everything here...
 one year ago

CalcmathleteBest ResponseYou've already chosen the best response.0
\[3\left[\begin{matrix}1 & 2 &3\\ 2 & 3 &0\\3&1&1\end{matrix}\right]  2\left[\begin{matrix}1 & 2 &1\\ 2 & 3 &2\\3&1&0\end{matrix}\right]\]Did you end up doing this?
 one year ago

TuringTestBest ResponseYou've already chosen the best response.1
must be method of cofactors, eh?
 one year ago

asnaseerBest ResponseYou've already chosen the best response.2
I get 72. But maybe I made a mistake. Might be worth looking at this to help: http://people.richland.edu/james/lecture/m116/matrices/determinant.html
 one year ago

asnaseerBest ResponseYou've already chosen the best response.2
Look down that web page at the section titled "Larger Order Determinants"
 one year ago

TuringTestBest ResponseYou've already chosen the best response.1
another source for ya http://tutorial.math.lamar.edu/Classes/LinAlg/MethodOfCofactors.aspx
 one year ago

CalcmathleteBest ResponseYou've already chosen the best response.0
Well, 72 is one of my answer choices... I did it again, but I got  72? I think it's just an arithmetic error on my part. THanks guys!
 one year ago

asnaseerBest ResponseYou've already chosen the best response.2
yw :)  crosses fingers in the hope that he did make a mistake :)
 one year ago

CalcmathleteBest ResponseYou've already chosen the best response.0
Wait, one last thing, when I find the determinants of the 3 x 3, can I just use the diagonal method (I'm not sure of the name) or do I have to use minors?
 one year ago

asnaseerBest ResponseYou've already chosen the best response.2
as @TuringTest said, use the method of cofactors  see the links we gave you.
 one year ago

CalcmathleteBest ResponseYou've already chosen the best response.0
Ok, once again, thank you :)
 one year ago

TuringTestBest ResponseYou've already chosen the best response.1
the problem in what you did is that you forgot that all elements on the diagonals will give positive minors.
 one year ago

TuringTestBest ResponseYou've already chosen the best response.1
I phrased that poorly, not sure how to say it without giving away the answer
 one year ago

asnaseerBest ResponseYou've already chosen the best response.2
Also, determinants are usually written with straight lines on either side of the matrix elements  instead of the square brackets that you used.
 one year ago

CalcmathleteBest ResponseYou've already chosen the best response.0
Oh! I got it! And @asnaseer for some reason, I see them written both ways when doing school work?
 one year ago

asnaseerBest ResponseYou've already chosen the best response.2
Hmmm  ok, well I was taught that straight lines is what should be used. Maybe the notation differs from country to country?
 one year ago

TuringTestBest ResponseYou've already chosen the best response.1
if it's left in brackets it should at least say \(\det\) in front of it In the US we use what @asnaseer said
 one year ago

asnaseerBest ResponseYou've already chosen the best response.2
Here is an example of how we are taught in the UK: http://www.intmath.com/matricesdeterminants/matrixdeterminantintro.php
 one year ago

asnaseerBest ResponseYou've already chosen the best response.2
Also, when working with algebra, if you have a matrix A, then we would write its determinant as either:\[A\]or:\[det(A)\]
 one year ago
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