document.write( "Question 200660: Hi all I asked a similiar question recently and got a reaaly good response, but this imiliar problem is still giving me trouble.
\n" ); document.write( "I need to solve the following Matrices and comment on the outcomes.For the following:
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\n" ); document.write( "Find and state why or why not the following is possible.
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\n" ); document.write( "iii) AB
\n" ); document.write( "1v) B^C
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Algebra.Com's Answer #151046 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
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Part i)
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\n" ); document.write( "\n" ); document.write( "Given Matrices:\r
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\n" ); document.write( "\n" ); document.write( "\"A=%28matrix%282%2C3%2C2%2C3%2C0%2C1%2C4%2C-3%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"B=%28matrix%282%2C3%2C1%2C-1%2C4%2C2%2C3%2C5%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "\"C=%28matrix%282%2C2%2C2%2C-1%2C3%2C5%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Part i)\r
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\n" ); document.write( "\n" ); document.write( " Start with the addition of the two given matrices\r
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\n" ); document.write( "\n" ); document.write( "\"A%2BB=%28matrix%282%2C3%2C2%2B1%2C3%2B%28-1%29%2C0%2B4%2C1%2B2%2C4%2B3%2C-3%2B5%29%29\" Add up the matrices by adding the corresponding entries\r
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\n" ); document.write( "\n" ); document.write( "\"A%2BB=%28matrix%282%2C3%2C3%2C2%2C4%2C3%2C7%2C2%29%29\" Add\r
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\n" ); document.write( "\n" ); document.write( "Answer:\r
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\n" ); document.write( "\n" ); document.write( "So \"A%2BB=%28matrix%282%2C3%2C3%2C2%2C4%2C3%2C7%2C2%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Part ii)\r
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\n" ); document.write( "\n" ); document.write( "To find the inverse of the matrix \"C=%28matrix%282%2C2%2C2%2C-1%2C3%2C5%29%29\", we can follow these steps:\r
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\n" ); document.write( "\n" ); document.write( "Step 1) Find the determinant\r
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\n" ); document.write( "\n" ); document.write( "The determinant of \"%28matrix%282%2C2%2C2%2C-1%2C3%2C5%29%29\" is \"abs%28matrix%282%2C2%2C2%2C-1%2C3%2C5%29%29=13\". So this means that \"d=13\"\r
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\n" ); document.write( "\n" ); document.write( "note: since the determinant is NOT equal to zero, the matrix inverse exists.\r
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\n" ); document.write( "\n" ); document.write( "Step 2) Swap the values\r
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\n" ); document.write( "\n" ); document.write( "Now switch the highlighted values \"%28matrix%282%2C2%2Chighlight%282%29%2C-1%2C3%2Chighlight%285%29%29%29\" to get \"%28matrix%282%2C2%2Chighlight%285%29%2C-1%2C3%2Chighlight%282%29%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Step 3) Change the sign\r
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\n" ); document.write( "\n" ); document.write( "Now change the sign of the highlighted values \"%28matrix%282%2C2%2C5%2Chighlight%28-1%29%2Chighlight%283%29%2C2%29%29\" to get \"%28matrix%282%2C2%2C5%2Chighlight%281%29%2Chighlight%28-3%29%2C2%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Step 4) Multiply by the inverse of the determinant\r
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\n" ); document.write( "\n" ); document.write( "Multiply by \"1%2Fd\" to get \"%281%2Fd%29%28matrix%282%2C2%2C5%2C1%2C-3%2C2%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Plug in \"d=13\" to get \"%281%2F13%29%28matrix%282%2C2%2C5%2C1%2C-3%2C2%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Step 5) Perform scalar multiplication and simplify.\r
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\n" ); document.write( "\n" ); document.write( "Multiply \"1%2F13\" by EVERY element to get \r
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\n" ); document.write( "\n" ); document.write( "Multiply to get \"%28matrix%282%2C2%2C5%2F13%2C1%2F13%2C-3%2F13%2C2%2F13%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Answer:\r
\n" ); document.write( "\n" ); document.write( "So the inverse of \"%28matrix%282%2C2%2C2%2C-1%2C3%2C5%29%29\" is \"%28matrix%282%2C2%2C5%2F13%2C1%2F13%2C-3%2F13%2C2%2F13%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "This means that if \"C=%28matrix%282%2C2%2C2%2C-1%2C3%2C5%29%29\" then \"C%5E%28-1%29=%28matrix%282%2C2%2C5%2F13%2C1%2F13%2C-3%2F13%2C2%2F13%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "note: to verify your work, multiply the matrices \"C\" and \"C%5E%28-1%29\" and you should get the matrix \"%28matrix%282%2C2%2C1%2C0%2C0%2C1%29%29\" (the identity matrix).\r
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\n" ); document.write( "\n" ); document.write( "Part iii)\r
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\n" ); document.write( "\n" ); document.write( "Take note that the dimensions of matrices A and B are 2x3 and 2x3 respectively. Since the inner dimensions do NOT match, this means that the matrix product AB is NOT defined. In other words, AB does NOT exist.\r
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\n" ); document.write( "\n" ); document.write( "note: if A and B are mxn and nxp matrices, then the product AB is defined. It is only defined if the number of columns of A equals the number of rows of B. Otherwise, AB does NOT exist.\r
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\n" ); document.write( "\n" ); document.write( "So the matrix product AB is not defined (ie it doesn't exist).\r
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\n" ); document.write( "\n" ); document.write( "Part iv)\r
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\n" ); document.write( "\n" ); document.write( "I'm sure you meant to write \"B%5ET%2AC\" correct? If so, then...\r
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\n" ); document.write( "\n" ); document.write( "Step 1: Transpose matrix B to get \"B%5ET\". You do this by converting each row into a column (and vice versa).\r
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\n" ); document.write( "\n" ); document.write( "Step 2: Multiply matrices \"B%5ET\" and C. Since the inner dimensions are equal, this means that the matrix product \"B%5ET%2AC\" is defined.\r
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\n" ); document.write( "\n" ); document.write( "Since the first matrix is a 3 by 2 matrix and the second matrix is a 2 by 2 matrix, this means that the resulting matrix will be a 3 by 2 matrix.\r
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\n" ); document.write( "\n" ); document.write( "So the final resulting matrix will look like:\r
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\n" ); document.write( "\n" ); document.write( "\"B%5ET%2AC=%28matrix%283%2C2%2Cx%2Cx%2Cx%2Cx%2Cx%2Cx%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "note: the \"x\"s are just placeholders for now\r
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\n" ); document.write( "\n" ); document.write( "Multiply the corresponding entries from the 1st row of the first matrix by the 1st column of the second matrix. After multiplying, add the values:\r
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\n" ); document.write( "\n" ); document.write( "1st row, 1st column: \r
\n" ); document.write( "\n" ); document.write( "\"%281%29%2A%282%29%2B%282%29%2A%283%29=2%2B6=8\"\r
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\n" ); document.write( "\n" ); document.write( " So the element in the 1st row, 1st column of the resulting matrix is \"8\". Now let's update the matrix:\r
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\n" ); document.write( "\n" ); document.write( "\"B%5ET%2AC=%28matrix%283%2C2%2C8%2Cx%2Cx%2Cx%2Cx%2Cx%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Multiply the corresponding entries from the 1st row of the first matrix by the 2nd column of the second matrix. After multiplying, add the values:\r
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\n" ); document.write( "\n" ); document.write( "1st row, 2nd column: \r
\n" ); document.write( "\n" ); document.write( "\"%281%29%2A%28-1%29%2B%282%29%2A%285%29=-1%2B10=9\"\r
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\n" ); document.write( "\n" ); document.write( " So the element in the 1st row, 2nd column of the resulting matrix is \"9\". Now let's update the matrix:\r
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\n" ); document.write( "\n" ); document.write( "\"B%5ET%2AC=%28matrix%283%2C2%2C8%2C9%2Cx%2Cx%2Cx%2Cx%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Multiply the corresponding entries from the 2nd row of the first matrix by the 1st column of the second matrix. After multiplying, add the values:\r
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\n" ); document.write( "\n" ); document.write( "2nd row, 1st column: \r
\n" ); document.write( "\n" ); document.write( "\"%28-1%29%2A%282%29%2B%283%29%2A%283%29=-2%2B9=7\"\r
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\n" ); document.write( "\n" ); document.write( " So the element in the 2nd row, 1st column of the resulting matrix is \"7\". Now let's update the matrix:\r
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\n" ); document.write( "\n" ); document.write( "\"B%5ET%2AC=%28matrix%283%2C2%2C8%2C9%2C7%2Cx%2Cx%2Cx%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Multiply the corresponding entries from the 2nd row of the first matrix by the 2nd column of the second matrix. After multiplying, add the values:\r
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\n" ); document.write( "\n" ); document.write( "2nd row, 2nd column: \r
\n" ); document.write( "\n" ); document.write( "\"%28-1%29%2A%28-1%29%2B%283%29%2A%285%29=1%2B15=16\"\r
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\n" ); document.write( "\n" ); document.write( " So the element in the 2nd row, 2nd column of the resulting matrix is \"16\". Now let's update the matrix:\r
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\n" ); document.write( "\n" ); document.write( "\"B%5ET%2AC=%28matrix%283%2C2%2C8%2C9%2C7%2C16%2Cx%2Cx%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Multiply the corresponding entries from the 3rd row of the first matrix by the 1st column of the second matrix. After multiplying, add the values:\r
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\n" ); document.write( "\n" ); document.write( "\"%284%29%2A%282%29%2B%285%29%2A%283%29=8%2B15=23\"\r
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\n" ); document.write( "\n" ); document.write( " So the element in the 3rd row, 1st column of the resulting matrix is \"23\". Now let's update the matrix:\r
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\n" ); document.write( "\n" ); document.write( "\"B%5ET%2AC=%28matrix%283%2C2%2C8%2C9%2C7%2C16%2C23%2Cx%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Multiply the corresponding entries from the 3rd row of the first matrix by the 2nd column of the second matrix. After multiplying, add the values:\r
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\n" ); document.write( "\n" ); document.write( "3rd row, 2nd column: \r
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\n" ); document.write( "\n" ); document.write( "\"%284%29%2A%28-1%29%2B%285%29%2A%285%29=-4%2B25=21\"\r
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\n" ); document.write( "\n" ); document.write( " So the element in the 3rd row, 2nd column of the resulting matrix is \"21\". Now let's update the matrix:\r
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\n" ); document.write( "\n" ); document.write( "\"B%5ET%2AC+=+%28matrix%283%2C2%2C8%2C9%2C7%2C16%2C23%2C21%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "In other words,\r
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\n" ); document.write( "\n" ); document.write( "\"B%5ET%2AC+=+%28matrix%283%2C2%2C8%2C9%2C7%2C16%2C23%2C21%29%29\"\r
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