document.write( "Question 115285: 5x-4y=1
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Algebra.Com's Answer #83878 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
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Solved by pluggable solver: Solving a linear system of equations by subsitution

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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-4%2Ay=1\"
\n" ); document.write( " \"3%2Ax-6%2Ay=6\"
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\n" ); document.write( " Now in order to solve this system by using substitution, we need to solve (or isolate) one variable. I'm going to choose y.
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\n" ); document.write( " Solve for y for the first equation
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\n" ); document.write( " \"-4%2Ay=1-5%2Ax\"Subtract \"5%2Ax\" from both sides
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\n" ); document.write( " \"y=%281-5%2Ax%29%2F-4\" Divide both sides by -4.
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\n" ); document.write( " Which breaks down and reduces to
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\n" ); document.write( " \"y=-1%2F4%2B%285%2F4%29%2Ax\" Now we've fully isolated y
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\n" ); document.write( " Since y equals \"-1%2F4%2B%285%2F4%29%2Ax\" we can substitute the expression \"-1%2F4%2B%285%2F4%29%2Ax\" into y of the 2nd equation. This will eliminate y so we can solve for x.
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\n" ); document.write( " \"3%2Ax%2B-6%2Ahighlight%28%28-1%2F4%2B%285%2F4%29%2Ax%29%29=6\" Replace y with \"-1%2F4%2B%285%2F4%29%2Ax\". Since this eliminates y, we can now solve for x.
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\n" ); document.write( " \"3%2Ax-6%2A%28-1%2F4%29-6%285%2F4%29x=6\" Distribute -6 to \"-1%2F4%2B%285%2F4%29%2Ax\"
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\n" ); document.write( " \"3%2Ax%2B6%2F4-%2830%2F4%29%2Ax=6\" Multiply
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\n" ); document.write( " \"3%2Ax%2B3%2F2-%2815%2F2%29%2Ax=6\" Reduce any fractions
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\n" ); document.write( " \"3%2Ax-%2815%2F2%29%2Ax=6-3%2F2\" Subtract \"3%2F2\" from both sides
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\n" ); document.write( " \"3%2Ax-%2815%2F2%29%2Ax=12%2F2-3%2F2\" Make 6 into a fraction with a denominator of 2
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\n" ); document.write( " \"3%2Ax-%2815%2F2%29%2Ax=9%2F2\" Combine the terms on the right side
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\n" ); document.write( " \"%286%2F2%29%2Ax-%2815%2F2%29x=9%2F2\" Make 3 into a fraction with a denominator of 2
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\n" ); document.write( " \"%28-9%2F2%29%2Ax=9%2F2\" Now combine the terms on the left side.
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\n" ); document.write( " \"cross%28%282%2F-9%29%28-9%2F2%29%29x=%289%2F2%29%282%2F-9%29\" Multiply both sides by \"2%2F-9\". This will cancel out \"-9%2F2\" and isolate x
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\n" ); document.write( " So when we multiply \"9%2F2\" and \"2%2F-9\" (and simplify) we get
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\n" ); document.write( " \"x=-1\" <---------------------------------One answer
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\n" ); document.write( " Now that we know that \"x=-1\", lets substitute that in for x to solve for y
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\n" ); document.write( " \"3%28-1%29-6%2Ay=6\" Plug in \"x=-1\" into the 2nd equation
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\n" ); document.write( " \"-3-6%2Ay=6\" Multiply
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\n" ); document.write( " \"-6%2Ay=6%2B3\"Add \"3\" to both sides
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\n" ); document.write( " \"-6%2Ay=9\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F-6%29%28-6%29%29%2Ay=%289%2F1%29%281%2F-6%29\" Multiply both sides by \"1%2F-6\". This will cancel out -6 on the left side.
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\n" ); document.write( " \"y=9%2F-6\" Multiply the terms on the right side
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\n" ); document.write( " \"y=-3%2F2\" Reduce
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\n" ); document.write( " So this is the other answer
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\n" ); document.write( " \"y=-3%2F2\"<---------------------------------Other answer
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\n" ); document.write( " So our solution is
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\n" ); document.write( " \"x=-1\" and \"y=-3%2F2\"
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\n" ); document.write( " which can also look like
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\n" ); document.write( " (\"-1\",\"-3%2F2\")
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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-4%2Ay=1\"
\n" ); document.write( " \"3%2Ax-6%2Ay=6\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"5%2Ax-4%2Ay=1\" (red) and \"3%2Ax-6%2Ay=6\" (green) (hint: you may have to solve for y to graph these) intersecting at the blue circle.
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\n" ); document.write( " and we can see that the two equations intersect at (\"-1\",\"-3%2F2\"). This verifies our answer.
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\n" ); document.write( " Check:
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\n" ); document.write( " Plug in (\"-1\",\"-3%2F2\") into the system of equations
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\n" ); document.write( " Let \"x=-1\" and \"y=-3%2F2\". Now plug those values into the equation \"5%2Ax-4%2Ay=1\"
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\n" ); document.write( " \"5%2A%28-1%29-4%2A%28-3%2F2%29=1\" Plug in \"x=-1\" and \"y=-3%2F2\"
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\n" ); document.write( " \"-5%2B12%2F2=1\" Multiply
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\n" ); document.write( " \"2%2F2=1\" Add
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\n" ); document.write( " \"1=1\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"-1\",\"-3%2F2\") satisfies \"5%2Ax-4%2Ay=1\"
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\n" ); document.write( " Let \"x=-1\" and \"y=-3%2F2\". Now plug those values into the equation \"3%2Ax-6%2Ay=6\"
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\n" ); document.write( " \"3%2A%28-1%29-6%2A%28-3%2F2%29=6\" Plug in \"x=-1\" and \"y=-3%2F2\"
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\n" ); document.write( " \"-3%2B18%2F2=6\" Multiply
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\n" ); document.write( " \"12%2F2=6\" Add
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\n" ); document.write( " \"6=6\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"-1\",\"-3%2F2\") satisfies \"3%2Ax-6%2Ay=6\"
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\n" ); document.write( " Since the solution (\"-1\",\"-3%2F2\") satisfies the system of equations
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\n" ); document.write( " \"5%2Ax-4%2Ay=1\"
\n" ); document.write( " \"3%2Ax-6%2Ay=6\"
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\n" ); document.write( " this verifies our answer.
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