document.write( "Question 874041: Please help me solve this, I'm a bit confused.\r
\n" ); document.write( "\n" ); document.write( "Solve each system of equations using matrix equation. Explain step by step. Check answers.\r
\n" ); document.write( "\n" ); document.write( "x+y+z=4
\n" ); document.write( "4x+5y=3
\n" ); document.write( "y-3z=-10\r
\n" ); document.write( "\n" ); document.write( "(there is a big \"{\" around all three of them, if that matters)
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Algebra.Com's Answer #527354 by richwmiller(17219)\"\" \"About 
You can put this solution on YOUR website!
here is gauss jordan and cramer's rule
\n" ); document.write( "original 3*4 matrix
\n" ); document.write( "1,1,1,4
\n" ); document.write( "4,5,0,3
\n" ); document.write( "0,1,-3,-10\r
\n" ); document.write( "\n" ); document.write( "divide row 1 by 1
\n" ); document.write( "step 1
\n" ); document.write( "1,1,1,4
\n" ); document.write( "4,5,0,3
\n" ); document.write( "0,1,-3,-10\r
\n" ); document.write( "\n" ); document.write( "add -4*row 1 to row 2
\n" ); document.write( "step 2
\n" ); document.write( "1,1,1,4
\n" ); document.write( "0,1,-4,-13
\n" ); document.write( "0,1,-3,-10\r
\n" ); document.write( "\n" ); document.write( "add 0*row 1 to row 3
\n" ); document.write( "step 3
\n" ); document.write( "1,1,1,4
\n" ); document.write( "0,1,-4,-13
\n" ); document.write( "0,1,-3,-10\r
\n" ); document.write( "\n" ); document.write( "divide row 2 by 1
\n" ); document.write( "step 4
\n" ); document.write( "1,1,1,4
\n" ); document.write( "0,1,-4,-13
\n" ); document.write( "0,1,-3,-10\r
\n" ); document.write( "\n" ); document.write( "add -1*row 2 to row 3
\n" ); document.write( "step 5
\n" ); document.write( "1,1,1,4
\n" ); document.write( "0,1,-4,-13
\n" ); document.write( "0,0,1,3\r
\n" ); document.write( "\n" ); document.write( "divide row 3 by 1
\n" ); document.write( "step 6
\n" ); document.write( "1,1,1,4
\n" ); document.write( "0,1,-4,-13
\n" ); document.write( "0,0,1,3\r
\n" ); document.write( "\n" ); document.write( "add 4*row 3 to row 2
\n" ); document.write( "step 7
\n" ); document.write( "1,1,1,4
\n" ); document.write( "0,1,0,-1
\n" ); document.write( "0,0,1,3\r
\n" ); document.write( "\n" ); document.write( "add -1*row 3 to row 1
\n" ); document.write( "step 8
\n" ); document.write( "1,1,0,1
\n" ); document.write( "0,1,0,-1
\n" ); document.write( "0,0,1,3\r
\n" ); document.write( "\n" ); document.write( "add -1*row 2 to row 1
\n" ); document.write( "step 9
\n" ); document.write( "1,0,0,2
\n" ); document.write( "0,1,0,-1
\n" ); document.write( "0,0,1,3\r
\n" ); document.write( "\n" ); document.write( "\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "\n" ); document.write( "
Solved by pluggable solver: Using Cramer's Rule to Solve Systems with 3 variables

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\n" ); document.write( " \"system%281%2Ax%2B1%2Ay%2B1%2Az=4%2C4%2Ax%2B5%2Ay%2B0%2Az=3%2C0%2Ax%2B1%2Ay%2B-3%2Az=-10%29\"
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\n" ); document.write( " First let \"A=%28matrix%283%2C3%2C1%2C1%2C1%2C4%2C5%2C0%2C0%2C1%2C-3%29%29\". This is the matrix formed by the coefficients of the given system of equations.
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\n" ); document.write( " Take note that the right hand values of the system are \"4\", \"3\", and \"-10\" and they are highlighted here:
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\n" ); document.write( " These values are important as they will be used to replace the columns of the matrix A.
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\n" ); document.write( " Now let's calculate the the determinant of the matrix A to get \"abs%28A%29=1\". To save space, I'm not showing the calculations for the determinant. However, if you need help with calculating the determinant of the matrix A, check out this solver.
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\n" ); document.write( " Notation note: \"abs%28A%29\" denotes the determinant of the matrix A.
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\n" ); document.write( " Now replace the first column of A (that corresponds to the variable 'x') with the values that form the right hand side of the system of equations. We will denote this new matrix \"A%5Bx%5D\" (since we're replacing the 'x' column so to speak).
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\n" ); document.write( " Now compute the determinant of \"A%5Bx%5D\" to get \"abs%28A%5Bx%5D%29=2\". Again, as a space saver, I didn't include the calculations of the determinant. Check out this solver to see how to find this determinant.
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\n" ); document.write( " To find the first solution, simply divide the determinant of \"A%5Bx%5D\" by the determinant of \"A\" to get: \"x=%28abs%28A%5Bx%5D%29%29%2F%28abs%28A%29%29=%282%29%2F%281%29=2\"
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\n" ); document.write( " So the first solution is \"x=2\"
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\n" ); document.write( " We'll follow the same basic idea to find the other two solutions. Let's reset by letting \"A=%28matrix%283%2C3%2C1%2C1%2C1%2C4%2C5%2C0%2C0%2C1%2C-3%29%29\" again (this is the coefficient matrix).
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\n" ); document.write( " Now replace the second column of A (that corresponds to the variable 'y') with the values that form the right hand side of the system of equations. We will denote this new matrix \"A%5By%5D\" (since we're replacing the 'y' column in a way).
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\n" ); document.write( " Now compute the determinant of \"A%5By%5D\" to get \"abs%28A%5By%5D%29=-1\".
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\n" ); document.write( " To find the second solution, divide the determinant of \"A%5By%5D\" by the determinant of \"A\" to get: \"y=%28abs%28A%5By%5D%29%29%2F%28abs%28A%29%29=%28-1%29%2F%281%29=-1\"
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\n" ); document.write( " So the second solution is \"y=-1\"
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\n" ); document.write( " Let's reset again by letting \"A=%28matrix%283%2C3%2C1%2C1%2C1%2C4%2C5%2C0%2C0%2C1%2C-3%29%29\" which is the coefficient matrix.
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\n" ); document.write( " Replace the third column of A (that corresponds to the variable 'z') with the values that form the right hand side of the system of equations. We will denote this new matrix \"A%5Bz%5D\"
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\n" ); document.write( " Now compute the determinant of \"A%5Bz%5D\" to get \"abs%28A%5Bz%5D%29=3\".
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\n" ); document.write( " To find the third solution, divide the determinant of \"A%5Bz%5D\" by the determinant of \"A\" to get: \"z=%28abs%28A%5Bz%5D%29%29%2F%28abs%28A%29%29=%283%29%2F%281%29=3\"
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\n" ); document.write( " So the third solution is \"z=3\"
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\n" ); document.write( " Final Answer:
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\n" ); document.write( " So the three solutions are \"x=2\", \"y=-1\", and \"z=3\" giving the ordered triple (2, -1, 3)
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\n" ); document.write( " Note: there is a lot of work that is hidden in finding the determinants. Take a look at this 3x3 Determinant Solver to see how to get each determinant.
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