document.write( "Question 114022: 2x-5y=10
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Algebra.Com's Answer #82974 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( " \"2%2Ax-5%2Ay=10\"
\n" ); document.write( " \"4%2Ax%2B3%2Ay=7\"
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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( " \"-5%2Ay=10-2%2Ax\"Subtract \"2%2Ax\" from both sides
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\n" ); document.write( " \"y=%2810-2%2Ax%29%2F-5\" Divide both sides by -5.
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\n" ); document.write( " Which breaks down and reduces to
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\n" ); document.write( " \"y=-2%2B%282%2F5%29%2Ax\" Now we've fully isolated y
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\n" ); document.write( " Since y equals \"-2%2B%282%2F5%29%2Ax\" we can substitute the expression \"-2%2B%282%2F5%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( " \"4%2Ax%2B3%2Ahighlight%28%28-2%2B%282%2F5%29%2Ax%29%29=7\" Replace y with \"-2%2B%282%2F5%29%2Ax\". Since this eliminates y, we can now solve for x.
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\n" ); document.write( " \"4%2Ax%2B3%2A%28-2%29%2B3%282%2F5%29x=7\" Distribute 3 to \"-2%2B%282%2F5%29%2Ax\"
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\n" ); document.write( " \"4%2Ax-6%2B%286%2F5%29%2Ax=7\" Multiply
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\n" ); document.write( " \"4%2Ax-6%2B%286%2F5%29%2Ax=7\" Reduce any fractions
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\n" ); document.write( " \"4%2Ax%2B%286%2F5%29%2Ax=7%2B6\"Add \"6\" to both sides
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\n" ); document.write( " \"4%2Ax%2B%286%2F5%29%2Ax=13\" Combine the terms on the right side
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\n" ); document.write( " \"%2820%2F5%29%2Ax%2B%286%2F5%29x=13\" Make 4 into a fraction with a denominator of 5
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\n" ); document.write( " \"%2826%2F5%29%2Ax=13\" Now combine the terms on the left side.
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\n" ); document.write( " \"cross%28%285%2F26%29%2826%2F5%29%29x=%2813%2F1%29%285%2F26%29\" Multiply both sides by \"5%2F26\". This will cancel out \"26%2F5\" and isolate x
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\n" ); document.write( " So when we multiply \"13%2F1\" and \"5%2F26\" (and simplify) we get
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\n" ); document.write( " \"x=5%2F2\" <---------------------------------One answer
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\n" ); document.write( " Now that we know that \"x=5%2F2\", lets substitute that in for x to solve for y
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\n" ); document.write( " \"4%285%2F2%29%2B3%2Ay=7\" Plug in \"x=5%2F2\" into the 2nd equation
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\n" ); document.write( " \"10%2B3%2Ay=7\" Multiply
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\n" ); document.write( " \"3%2Ay=7-10\"Subtract \"10\" from both sides
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\n" ); document.write( " \"3%2Ay=-3\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F3%29%283%29%29%2Ay=%28-3%2F1%29%281%2F3%29\" Multiply both sides by \"1%2F3\". This will cancel out 3 on the left side.
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\n" ); document.write( " \"y=-3%2F3\" Multiply the terms on the right side
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\n" ); document.write( " \"y=-1\" Reduce
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\n" ); document.write( " So this is the other answer
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\n" ); document.write( " \"y=-1\"<---------------------------------Other answer
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\n" ); document.write( " So our solution is
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\n" ); document.write( " \"x=5%2F2\" and \"y=-1\"
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\n" ); document.write( " which can also look like
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\n" ); document.write( " (\"5%2F2\",\"-1\")
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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( " \"2%2Ax-5%2Ay=10\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"2%2Ax-5%2Ay=10\" (red) and \"4%2Ax%2B3%2Ay=7\" (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 (\"5%2F2\",\"-1\"). This verifies our answer.
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\n" ); document.write( " Check:
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\n" ); document.write( " Plug in (\"5%2F2\",\"-1\") into the system of equations
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\n" ); document.write( " Let \"x=5%2F2\" and \"y=-1\". Now plug those values into the equation \"2%2Ax-5%2Ay=10\"
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\n" ); document.write( " \"2%2A%285%2F2%29-5%2A%28-1%29=10\" Plug in \"x=5%2F2\" and \"y=-1\"
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\n" ); document.write( " \"10%2F2%2B5=10\" Multiply
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\n" ); document.write( " \"20%2F2=10\" Add
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\n" ); document.write( " \"10=10\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"5%2F2\",\"-1\") satisfies \"2%2Ax-5%2Ay=10\"
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\n" ); document.write( " Let \"x=5%2F2\" and \"y=-1\". Now plug those values into the equation \"4%2Ax%2B3%2Ay=7\"
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\n" ); document.write( " \"4%2A%285%2F2%29%2B3%2A%28-1%29=7\" Plug in \"x=5%2F2\" and \"y=-1\"
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\n" ); document.write( " \"20%2F2-3=7\" Multiply
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\n" ); document.write( " \"14%2F2=7\" Add
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\n" ); document.write( " \"7=7\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"5%2F2\",\"-1\") satisfies \"4%2Ax%2B3%2Ay=7\"
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\n" ); document.write( " Since the solution (\"5%2F2\",\"-1\") satisfies the system of equations
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\n" ); document.write( " \"2%2Ax-5%2Ay=10\"
\n" ); document.write( " \"4%2Ax%2B3%2Ay=7\"
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\n" ); document.write( " this verifies our answer.
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