document.write( "Question 1130422: Solve the system of equations by the elimination method. (If the system is dependent, let y = c and enter a general solution in terms of c. If there is no solution, enter NO SOLUTION.)
\n" ); document.write( "5/6x-1/3y+-21
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Algebra.Com's Answer #747089 by MathLover1(20849)\"\" \"About 
You can put this solution on YOUR website!

\n" ); document.write( "\"%285%2F6%29x-%281%2F3%29y-21=0\"
\n" ); document.write( "\"%281%2F6%29x%2B%282%2F3%29y%2B9=0\"\r
\n" ); document.write( "\n" ); document.write( "\"%285%2F6%29x-%281%2F3%29y=21\"
\n" ); document.write( "\"%281%2F6%29x%2B%282%2F3%29y=-9\"\r
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Solved by pluggable solver: Solving a System of Linear Equations by Elimination/Addition
TEST
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\n" ); document.write( " \"%285%2F6%29%2Ax%2B%281%2F3%29%2Ay=21\" Start with the first equation
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\n" ); document.write( " \"6%28%285%2F6%29%2Ax%2B%281%2F3%29%2Ay%29=%286%29%2A%2821%29\" Multiply both sides by the LCD 6
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\n" ); document.write( " \"5%2Ax%2B2%2Ay=126\"Distribute and simplify
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\n" ); document.write( " \"%281%2F6%29%2Ax%2B%282%2F3%29%2Ay=-9\" Start with the second equation
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\n" ); document.write( " \"6%28%281%2F6%29%2Ax%2B%282%2F3%29%2Ay%29=%286%29%2A%28-9%29\" Multiply both sides by the LCD 6
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\n" ); document.write( " \"1%2Ax%2B4%2Ay=-54\" Distribute and simplify
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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%2B2%2Ay=126\"
\n" ); document.write( " \"1%2Ax%2B4%2Ay=-54\"
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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%2B2%2Ay%29=%28126%29%2A1\" Multiply the top equation (both sides) by 1
\n" ); document.write( " \"-5%2A%281%2Ax%2B4%2Ay%29=%28-54%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%2B2%2Ay=126\"
\n" ); document.write( " \"-5%2Ax-20%2Ay=270\"
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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%2B%282%2Ay-20%2Ay%29=126%2B270\"
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\n" ); document.write( " \"%285-5%29%2Ax%2B%282-20%29y=126%2B270\"
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\n" ); document.write( " \"cross%285%2B-5%29%2Ax%2B%282-20%29%2Ay=126%2B270\" 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( " \"-18%2Ay=396\"
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\n" ); document.write( " \"y=396%2F-18\" Divide both sides by \"-18\" to solve for y
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\n" ); document.write( " \"y=-22\" Reduce
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\n" ); document.write( " Now plug this answer into the top equation \"5%2Ax%2B2%2Ay=126\" to solve for x
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\n" ); document.write( " \"5%2Ax%2B2%28-22%29=126\" Plug in \"y=-22\"
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\n" ); document.write( " \"5%2Ax-44=126\" Multiply
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\n" ); document.write( " \"5%2Ax=126%2B44\" Subtract \"-44\" from both sides
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\n" ); document.write( " \"5%2Ax=170\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F5%29%285%29%29%2Ax=%28170%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=34\" 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=34\", \"y=-22\"
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\n" ); document.write( " which also looks like
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\n" ); document.write( " (\"34\", \"-22\")
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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%2B2%2Ay=126\"
\n" ); document.write( " \"1%2Ax%2B4%2Ay=-54\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"5%2Ax%2B2%2Ay=126\" (red) \"1%2Ax%2B4%2Ay=-54\" (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 (\"34\",\"-22\"). This verifies our answer.
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\n" ); document.write( "\n" ); document.write( "answer:\r
\n" ); document.write( "\n" ); document.write( "(\"x\",\"+y\") =(\"34\",\"+-22\") \r
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