document.write( "Question 202458: Can anyone help me with these problems please?\r
\n" ); document.write( "\n" ); document.write( "1) Use the matrix method to solve:\r
\n" ); document.write( "\n" ); document.write( "5x + 3y = 3
\n" ); document.write( "2x - 6y = 30\r
\n" ); document.write( "\n" ); document.write( "x = ____
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\n" ); document.write( "\n" ); document.write( "2) Perform the following operations on matrices.\r
\n" ); document.write( "\n" ); document.write( "(4) + (8) = (____)
\n" ); document.write( "(7) (2) (____)\r
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\n" ); document.write( "\n" ); document.write( "3) Perform the following operations on matrices.\r
\n" ); document.write( "\n" ); document.write( "(1 8)(7 6) = (___ ___)
\n" ); document.write( "(0 7)(7 4) (___ ___)\r
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\n" ); document.write( "\n" ); document.write( "Thank you in advance for all your help.
\n" ); document.write( "~Sarah
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Algebra.Com's Answer #152689 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
# 1\r
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\n" ); document.write( "\n" ); document.write( "\"system%285x+%2B+3y+=+3%2C2x+-+6y+=+30%29\"\r
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\n" ); document.write( "\n" ); document.write( "into the matrix equation\r
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\n" ); document.write( "\n" ); document.write( "So what we now need is inverse matrix of \"%28matrix%282%2C2%2C5%2C3%2C2%2C-6%29%29\" to isolate \"%28matrix%282%2C1%2Cx%2Cy%29%29\"\r
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Solved by pluggable solver: Finding the Inverse of a 2x2 Matrix

To find the inverse of the matrix \"A=%28matrix%282%2C2%2C5%2C3%2C2%2C-6%29%29\", we can follow these steps:

Step 1) Find the determinant



The determinant of \"%28matrix%282%2C2%2C5%2C3%2C2%2C-6%29%29\" is \"abs%28matrix%282%2C2%2C5%2C3%2C2%2C-6%29%29=-36\". So this means that \"d=-36\"

Step 2) Swap the values



Now switch the highlighted values \"%28matrix%282%2C2%2Chighlight%285%29%2C3%2C2%2Chighlight%28-6%29%29%29\" to get \"%28matrix%282%2C2%2Chighlight%28-6%29%2C3%2C2%2Chighlight%285%29%29%29\"

Step 3) Change the sign



Now change the sign of the highlighted values \"%28matrix%282%2C2%2C-6%2Chighlight%283%29%2Chighlight%282%29%2C5%29%29\" to get \"%28matrix%282%2C2%2C-6%2Chighlight%28-3%29%2Chighlight%28-2%29%2C5%29%29\"

Step 4) Multiply by the inverse of the determinant



Multiply by \"1%2Fd\" to get \"%281%2Fd%29%28matrix%282%2C2%2C-6%2C-3%2C-2%2C5%29%29\"

Plug in \"d=-36\" to get \"%28-1%2F36%29%28matrix%282%2C2%2C-6%2C-3%2C-2%2C5%29%29\"

Step 5) Multiply \"-1%2F36\" by every element in the matrix (simplify and reduce if possible)



Multiply \"-1%2F36\" by EVERY element to get

Multiply to get \"%28matrix%282%2C2%2C-6%2F-36%2C-3%2F-36%2C-2%2F-36%2C5%2F-36%29%29\"

Reduce each element: \"%28matrix%282%2C2%2C1%2F6%2C1%2F12%2C1%2F18%2C-5%2F36%29%29\"


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Answer:

So the inverse of \"%28matrix%282%2C2%2C5%2C3%2C2%2C-6%29%29\" is \"%28matrix%282%2C2%2C1%2F6%2C1%2F12%2C1%2F18%2C-5%2F36%29%29\"

This means that if \"A=%28matrix%282%2C2%2C5%2C3%2C2%2C-6%29%29\" then \"A%5E%28-1%29=%28matrix%282%2C2%2C1%2F6%2C1%2F12%2C1%2F18%2C-5%2F36%29%29\"

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\n" ); document.write( "\n" ); document.write( "Now left multiply both sides by the inverse matrix to get\r
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\n" ); document.write( "\n" ); document.write( "\"%28matrix%282%2C1%2Cx%2Cy%29%29=%28matrix%282%2C2%2C3%2C-4%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "So this means that \"x=3\" and \"y=-4\"\r
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\n" ); document.write( "\n" ); document.write( "Note: let me know if you need help with matrix multiplication.\r
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\n" ); document.write( "\n" ); document.write( "# 2\r
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\n" ); document.write( "\n" ); document.write( "Simply add the corresponding components:\r
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\n" ); document.write( "\n" ); document.write( "# 3\r
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\n" ); document.write( "\n" ); document.write( "Since the first matrix is a 2 by 2 matrix and the second matrix is a 2 by 2 matrix, this means that the resulting matrix will be a 2 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( "\"%28matrix%282%2C2%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%287%29%2B%288%29%2A%287%29=7%2B56=63\"\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 \"63\". Now let's update the matrix:\r
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\n" ); document.write( "\n" ); document.write( "\"%28matrix%282%2C2%2C63%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( "\"%281%29%2A%286%29%2B%288%29%2A%284%29=6%2B32=38\"\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 \"38\". Now let's update the matrix:\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( "\"%280%29%2A%287%29%2B%287%29%2A%287%29=0%2B49=49\"\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 \"49\". Now let's update the matrix:\r
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\n" ); document.write( "\n" ); document.write( "\"%28matrix%282%2C2%2C63%2C38%2C49%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( "\"%280%29%2A%286%29%2B%287%29%2A%284%29=0%2B28=28\"\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 \"28\". Now let's update the matrix:\r
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\n" ); document.write( "\n" ); document.write( "\"%28matrix%282%2C2%2C63%2C38%2C49%2C28%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "Answer:\r
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\n" ); document.write( "\n" ); document.write( "So the solution is \"%28matrix%282%2C2%2C63%2C38%2C49%2C28%29%29\"\r
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\n" ); document.write( "\n" ); document.write( "In other words,\r
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