<p>Can anyone explain them to me? Also, should I compute them by hand or with a calculator?</p>
<p>Responses greatly appreciated.</p>
<p>a matrix is a bunch of numbers arranged into a 2d array.</p>
<p>To add two matrices of the same size (same # of rows and columns), add each entry together. Ditto for subtraction and dot operators.</p>
<p>To multiply two matrices where the number of columns of first matrix = number of rows of second matrix, take the ith row of the first matrix and find its dot product with the jth column of the second matrix and write it into the ijth entry in the answer.</p>
<p>Definitely use calculators. Matrices are annoying to do by hand.</p>
<p>If it's a 2 by 2 then the determinant is AxD-BxC
[A B]
[C D]</p>
<p>If it's a 3 by 3 it's a bit harder.
[A B C]
[D E F]
[G H I] </p>
<p>What you do is copy the first 2 columns.</p>
<p>[A B C][A B]
[D E F][D E]
[G H I][G H] </p>
<p>Then you start multiplying by diagonals and adding them out like this:
(AxExI + BxFxG + CxDxH) - (BxDxI + AxFxH + CxExG) and that's the determinant.</p>
<p>Do matrices appear on the test? If so, how? Would they ask you to simply multiply two matrices together? </p>
<p>Also, how can I employ my ti-83 to solve matrices?</p>
<p>Thanks Again</p>