document.write( "Question 153360: Can you please help me solve this sytem of equations?
\n" ); document.write( "6x-5y=3
\n" ); document.write( "4x+2y=-14
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Algebra.Com's Answer #112881 by jim_thompson5910(35256)\"\" \"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( " \"6%2Ax-5%2Ay=3\"
\n" ); document.write( " \"4%2Ax%2B2%2Ay=-14\"
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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 6 and 4 to some equal number, we could try to get them to the LCM.
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\n" ); document.write( " Since the LCM of 6 and 4 is 12, we need to multiply both sides of the top equation by 2 and multiply both sides of the bottom equation by -3 like this:
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\n" ); document.write( " \"2%2A%286%2Ax-5%2Ay%29=%283%29%2A2\" Multiply the top equation (both sides) by 2
\n" ); document.write( " \"-3%2A%284%2Ax%2B2%2Ay%29=%28-14%29%2A-3\" Multiply the bottom equation (both sides) by -3
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\n" ); document.write( " So after multiplying we get this:
\n" ); document.write( " \"12%2Ax-10%2Ay=6\"
\n" ); document.write( " \"-12%2Ax-6%2Ay=42\"
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\n" ); document.write( " Notice how 12 and -12 add to zero (ie \"12%2B-12=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( " \"%2812%2Ax-12%2Ax%29-10%2Ay-6%2Ay%29=6%2B42\"
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\n" ); document.write( " \"%2812-12%29%2Ax-10-6%29y=6%2B42\"
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\n" ); document.write( " \"cross%2812%2B-12%29%2Ax%2B%28-10-6%29%2Ay=6%2B42\" 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( " \"-16%2Ay=48\"
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\n" ); document.write( " \"y=48%2F-16\" Divide both sides by \"-16\" to solve for y
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\n" ); document.write( " \"y=-3\" Reduce
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\n" ); document.write( " Now plug this answer into the top equation \"6%2Ax-5%2Ay=3\" to solve for x
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\n" ); document.write( " \"6%2Ax-5%28-3%29=3\" Plug in \"y=-3\"
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\n" ); document.write( " \"6%2Ax%2B15=3\" Multiply
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\n" ); document.write( " \"6%2Ax=3-15\" Subtract \"15\" from both sides
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\n" ); document.write( " \"6%2Ax=-12\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F6%29%286%29%29%2Ax=%28-12%29%281%2F6%29\" Multiply both sides by \"1%2F6\". This will cancel out \"6\" on the left side.
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\n" ); document.write( " \"x=-2\" 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=-2\", \"y=-3\"
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\n" ); document.write( " which also looks like
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\n" ); document.write( " (\"-2\", \"-3\")
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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( " \"6%2Ax-5%2Ay=3\"
\n" ); document.write( " \"4%2Ax%2B2%2Ay=-14\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"6%2Ax-5%2Ay=3\" (red) \"4%2Ax%2B2%2Ay=-14\" (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 (\"-2\",\"-3\"). This verifies our answer.
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