document.write( "Question 610807: Using cramers rule: 6x+2y=-1 and -x+10y=5
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Algebra.Com's Answer #384592 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
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Solved by pluggable solver: Using Cramer's Rule to Solve Systems with 2 variables

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\n" ); document.write( " \"system%286%2Ax%2B2%2Ay=-1%2C-1%2Ax%2B10%2Ay=5%29\"
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\n" ); document.write( " First let \"A=%28matrix%282%2C2%2C6%2C2%2C-1%2C10%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 \"-1\" and \"5\" which are highlighted here:
\n" ); document.write( " \"system%286%2Ax%2B2%2Ay=highlight%28-1%29%2C-1%2Ax%2B10%2Ay=highlight%285%29%29\"
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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=%286%29%2810%29-%282%29%28-1%29=62\". Remember that the determinant of the 2x2 matrix \"A=%28matrix%282%2C2%2Ca%2Cb%2Cc%2Cd%29%29\" is \"abs%28A%29=ad-bc\". If you need help with calculating the determinant of any two by two matrices, then 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( " \"A%5Bx%5D=%28matrix%282%2C2%2Chighlight%28-1%29%2C2%2Chighlight%285%29%2C10%29%29\"
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\n" ); document.write( " Now compute the determinant of \"A%5Bx%5D\" to get \"abs%28A%5Bx%5D%29=%28-1%29%2810%29-%282%29%285%29=-20\". Once again, remember that the determinant of the 2x2 matrix \"A=%28matrix%282%2C2%2Ca%2Cb%2Cc%2Cd%29%29\" is \"abs%28A%29=ad-bc\"
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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=%28-20%29%2F%2862%29=-10%2F31\"
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\n" ); document.write( " So the first solution is \"x=-10%2F31\"
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\n" ); document.write( " We'll follow the same basic idea to find the other solution. Let's reset by letting \"A=%28matrix%282%2C2%2C6%2C2%2C-1%2C10%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( " \"A%5Bx%5D=%28matrix%282%2C2%2C6%2Chighlight%28-1%29%2C-1%2Chighlight%285%29%29%29\"
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\n" ); document.write( " Now compute the determinant of \"A%5By%5D\" to get \"abs%28A%5By%5D%29=%286%29%285%29-%28-1%29%28-1%29=29\".
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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=%2829%29%2F%2862%29=29%2F62\"
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\n" ); document.write( " So the second solution is \"y=29%2F62\"
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\n" ); document.write( " Final Answer:
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\n" ); document.write( " So the solutions are \"x=-10%2F31\" and \"y=29%2F62\" giving the ordered pair (-10/31, 29/62)
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\n" ); document.write( " Once again, Cramer's Rule is dependent on determinants. Take a look at this 2x2 Determinant Solver if you need more practice with determinants.
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