document.write( "Question 120401: Solve for X and Y in the following problems. \r
\n" ); document.write( "\n" ); document.write( "a. X + Y=6 ; 2X + Y = 8\r
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Algebra.Com's Answer #88244 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( " \"1%2Ax%2B1%2Ay=6\"
\n" ); document.write( " \"2%2Ax%2B1%2Ay=8\"
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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( " \"1%2Ay=6-1%2Ax\"Subtract \"1%2Ax\" from both sides
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\n" ); document.write( " \"y=%286-1%2Ax%29\" Divide both sides by 1.
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\n" ); document.write( " Which breaks down and reduces to
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\n" ); document.write( " \"y=6-1%2Ax\" Now we've fully isolated y
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\n" ); document.write( " Since y equals \"6-1%2Ax\" we can substitute the expression \"6-1%2Ax\" into y of the 2nd equation. This will eliminate y so we can solve for x.
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\n" ); document.write( " \"2%2Ax%2B1%2Ahighlight%28%286-1%2Ax%29%29=8\" Replace y with \"6-1%2Ax\". Since this eliminates y, we can now solve for x.
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\n" ); document.write( " \"2%2Ax%2B1%2A%286%29%2B1%28-1%29x=8\" Distribute 1 to \"6-1%2Ax\"
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\n" ); document.write( " \"2%2Ax%2B6-1%2Ax=8\" Multiply
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\n" ); document.write( " \"2%2Ax%2B6-1%2Ax=8\" Reduce any fractions
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\n" ); document.write( " \"2%2Ax-1%2Ax=8-6\" Subtract \"6\" from both sides
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\n" ); document.write( " \"2%2Ax-1%2Ax=2\" Combine the terms on the right side
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\n" ); document.write( " \"1%2Ax=2\" Now combine the terms on the left side.
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\n" ); document.write( " \"cross%28%281%2F1%29%281%2F1%29%29x=%282%2F1%29%281%2F1%29\" Multiply both sides by \"1%2F1\". This will cancel out \"1%2F1\" and isolate x
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\n" ); document.write( " So when we multiply \"2%2F1\" and \"1%2F1\" (and simplify) we get
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\n" ); document.write( " \"x=2\" <---------------------------------One answer
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\n" ); document.write( " Now that we know that \"x=2\", lets substitute that in for x to solve for y
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\n" ); document.write( " \"2%282%29%2B1%2Ay=8\" Plug in \"x=2\" into the 2nd equation
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\n" ); document.write( " \"4%2B1%2Ay=8\" Multiply
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\n" ); document.write( " \"1%2Ay=8-4\"Subtract \"4\" from both sides
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\n" ); document.write( " \"1%2Ay=4\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F1%29%281%29%29%2Ay=%284%2F1%29%281%2F1%29\" Multiply both sides by \"1%2F1\". This will cancel out 1 on the left side.
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\n" ); document.write( " \"y=4%2F1\" Multiply the terms on the right side
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\n" ); document.write( " \"y=4\" Reduce
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\n" ); document.write( " So this is the other answer
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\n" ); document.write( " \"y=4\"<---------------------------------Other answer
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\n" ); document.write( " So our solution is
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\n" ); document.write( " \"x=2\" and \"y=4\"
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\n" ); document.write( " which can also look like
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\n" ); document.write( " (\"2\",\"4\")
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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( " \"1%2Ax%2B1%2Ay=6\"
\n" ); document.write( " \"2%2Ax%2B1%2Ay=8\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"1%2Ax%2B1%2Ay=6\" (red) and \"2%2Ax%2B1%2Ay=8\" (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 (\"2\",\"4\"). This verifies our answer.
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\n" ); document.write( " Plug in (\"2\",\"4\") into the system of equations
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\n" ); document.write( " Let \"x=2\" and \"y=4\". Now plug those values into the equation \"1%2Ax%2B1%2Ay=6\"
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\n" ); document.write( " \"1%2A%282%29%2B1%2A%284%29=6\" Plug in \"x=2\" and \"y=4\"
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\n" ); document.write( " \"2%2B4=6\" Multiply
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\n" ); document.write( " \"6=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 (\"2\",\"4\") satisfies \"1%2Ax%2B1%2Ay=6\"
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\n" ); document.write( " Let \"x=2\" and \"y=4\". Now plug those values into the equation \"2%2Ax%2B1%2Ay=8\"
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\n" ); document.write( " \"2%2A%282%29%2B1%2A%284%29=8\" Plug in \"x=2\" and \"y=4\"
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\n" ); document.write( " \"4%2B4=8\" Multiply
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\n" ); document.write( " \"8=8\" Add
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\n" ); document.write( " \"8=8\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"2\",\"4\") satisfies \"2%2Ax%2B1%2Ay=8\"
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\n" ); document.write( " Since the solution (\"2\",\"4\") satisfies the system of equations
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\n" ); document.write( " \"1%2Ax%2B1%2Ay=6\"
\n" ); document.write( " \"2%2Ax%2B1%2Ay=8\"
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\n" ); document.write( " this verifies our answer.
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