document.write( "Question 868575: X+ 2y+a=-1
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Algebra.Com's Answer #523661 by ewatrrr(24785)\"\" \"About 
You can put this solution on YOUR website!

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document.write( "x=9/4, y=-3/4, and a=-7/4 
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Solved by pluggable solver: Using Cramer's Rule to Solve Systems with 3 variables

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document.write( "  \"system%281%2Ax%2B2%2Ay%2B1%2Az=-1%2C1%2Ax%2B-3%2Ay%2B2%2Az=1%2C2%2Ax%2B-3%2Ay%2B1%2Az=5%29\"
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document.write( "  First let \"A=%28matrix%283%2C3%2C1%2C2%2C1%2C1%2C-3%2C2%2C2%2C-3%2C1%29%29\". This is the matrix formed by the coefficients of the given system of equations.
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document.write( "  Take note that the right hand values of the system are \"-1\", \"1\", and \"5\" and they are highlighted here: 
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document.write( "  These values are important as they will be used to replace the columns of the matrix A.
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document.write( "  Now let's calculate the the determinant of the matrix A to get \"abs%28A%29=12\". 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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document.write( "  Notation note: \"abs%28A%29\" denotes the determinant of the matrix A.
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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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document.write( "  Now compute the determinant of \"A%5Bx%5D\" to get \"abs%28A%5Bx%5D%29=27\". 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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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=%2827%29%2F%2812%29=9%2F4\"
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document.write( "  So the first solution is \"x=9%2F4\"
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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%2C2%2C1%2C1%2C-3%2C2%2C2%2C-3%2C1%29%29\" again (this is the coefficient matrix).
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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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document.write( "  Now compute the determinant of \"A%5By%5D\" to get \"abs%28A%5By%5D%29=-9\".
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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=%28-9%29%2F%2812%29=-3%2F4\"
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document.write( "  So the second solution is \"y=-3%2F4\"
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document.write( "  Let's reset again by letting \"A=%28matrix%283%2C3%2C1%2C2%2C1%2C1%2C-3%2C2%2C2%2C-3%2C1%29%29\" which is the coefficient matrix.
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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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document.write( "  Now compute the determinant of \"A%5Bz%5D\" to get \"abs%28A%5Bz%5D%29=-21\".
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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=%28-21%29%2F%2812%29=-7%2F4\"
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document.write( "  So the third solution is \"z=-7%2F4\"
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document.write( "  ====================================================================================
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document.write( "  Final Answer:
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document.write( "  So the three solutions are \"x=9%2F4\", \"y=-3%2F4\", and \"z=-7%2F4\" giving the ordered triple (9/4, -3/4, -7/4)
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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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