document.write( "Question 944792: Please help me with this equation using Elimination Method
\n" ); document.write( "5x-2y= 6
\n" ); document.write( " x+3y= -2
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Algebra.Com's Answer #576076 by MathLover1(20850)\"\" \"About 
You can put this solution on YOUR website!
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Solved by pluggable solver: Solving a System of Linear Equations by Elimination/Addition

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\n" ); document.write( " Lets start with the given system of linear equations
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\n" ); document.write( " \"5%2Ax-2%2Ay=6\"
\n" ); document.write( " \"1%2Ax%2B3%2Ay=-2\"
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\n" ); document.write( " In order to solve for one variable, we must eliminate the other variable. So if we wanted to solve for y, we would have to eliminate x (or vice versa).
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\n" ); document.write( " So lets eliminate x. In order to do that, we need to have both x coefficients that are equal but have opposite signs (for instance 2 and -2 are equal but have opposite signs). This way they will add to zero.
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\n" ); document.write( " So to make the x coefficients equal but opposite, we need to multiply both x coefficients by some number to get them to an equal number. So if we wanted to get 5 and 1 to some equal number, we could try to get them to the LCM.
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\n" ); document.write( " Since the LCM of 5 and 1 is 5, we need to multiply both sides of the top equation by 1 and multiply both sides of the bottom equation by -5 like this:
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\n" ); document.write( " \"1%2A%285%2Ax-2%2Ay%29=%286%29%2A1\" Multiply the top equation (both sides) by 1
\n" ); document.write( " \"-5%2A%281%2Ax%2B3%2Ay%29=%28-2%29%2A-5\" Multiply the bottom equation (both sides) by -5
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\n" ); document.write( " So after multiplying we get this:
\n" ); document.write( " \"5%2Ax-2%2Ay=6\"
\n" ); document.write( " \"-5%2Ax-15%2Ay=10\"
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\n" ); document.write( " Notice how 5 and -5 add to zero (ie \"5%2B-5=0\")
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\n" ); document.write( " Now add the equations together. In order to add 2 equations, group like terms and combine them
\n" ); document.write( " \"%285%2Ax-5%2Ax%29-2%2Ay-15%2Ay%29=6%2B10\"
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\n" ); document.write( " \"%285-5%29%2Ax-2-15%29y=6%2B10\"
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\n" ); document.write( " \"cross%285%2B-5%29%2Ax%2B%28-2-15%29%2Ay=6%2B10\" Notice the x coefficients add to zero and cancel out. This means we've eliminated x altogether.
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\n" ); document.write( " So after adding and canceling out the x terms we're left with:
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\n" ); document.write( " \"-17%2Ay=16\"
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\n" ); document.write( " \"y=16%2F-17\" Divide both sides by \"-17\" to solve for y
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\n" ); document.write( " \"y=-16%2F17\" Reduce
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\n" ); document.write( " Now plug this answer into the top equation \"5%2Ax-2%2Ay=6\" to solve for x
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\n" ); document.write( " \"5%2Ax-2%28-16%2F17%29=6\" Plug in \"y=-16%2F17\"
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\n" ); document.write( " \"5%2Ax%2B32%2F17=6\" Multiply
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\n" ); document.write( " \"5%2Ax%2B32%2F17=6\" Reduce
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\n" ); document.write( " \"5%2Ax=6-32%2F17\" Subtract \"32%2F17\" from both sides
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\n" ); document.write( " \"5%2Ax=102%2F17-32%2F17\" Make 6 into a fraction with a denominator of 17
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\n" ); document.write( " \"5%2Ax=70%2F17\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F5%29%285%29%29%2Ax=%2870%2F17%29%281%2F5%29\" Multiply both sides by \"1%2F5\". This will cancel out \"5\" on the left side.
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\n" ); document.write( " \"x=14%2F17\" Multiply the terms on the right side
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\n" ); document.write( " So our answer is
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\n" ); document.write( " \"x=14%2F17\", \"y=-16%2F17\"
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\n" ); document.write( " which also looks like
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\n" ); document.write( " (\"14%2F17\", \"-16%2F17\")
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\n" ); document.write( " Notice if we graph the equations (if you need help with graphing, check out this solver)
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\n" ); document.write( " \"5%2Ax-2%2Ay=6\"
\n" ); document.write( " \"1%2Ax%2B3%2Ay=-2\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"5%2Ax-2%2Ay=6\" (red) \"1%2Ax%2B3%2Ay=-2\" (green) (hint: you may have to solve for y to graph these) and the intersection of the lines (blue circle).
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\n" ); document.write( " and we can see that the two equations intersect at (\"14%2F17\",\"-16%2F17\"). This verifies our answer.
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