document.write( "Question 118241: x+3y=2
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Algebra.Com's Answer #86346 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%2B3%2Ay=2\"
\n" ); document.write( " \"-1%2Ax%2B1%2Ay=1\"
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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( " \"3%2Ay=2-1%2Ax\"Subtract \"1%2Ax\" from both sides
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\n" ); document.write( " \"y=%282-1%2Ax%29%2F3\" Divide both sides by 3.
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\n" ); document.write( " Which breaks down and reduces to
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\n" ); document.write( " \"y=2%2F3-%281%2F3%29%2Ax\" Now we've fully isolated y
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\n" ); document.write( " Since y equals \"2%2F3-%281%2F3%29%2Ax\" we can substitute the expression \"2%2F3-%281%2F3%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( " \"-1%2Ax%2B1%2Ahighlight%28%282%2F3-%281%2F3%29%2Ax%29%29=1\" Replace y with \"2%2F3-%281%2F3%29%2Ax\". Since this eliminates y, we can now solve for x.
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\n" ); document.write( " \"-1%2Ax%2B1%2A%282%2F3%29%2B1%28-1%2F3%29x=1\" Distribute 1 to \"2%2F3-%281%2F3%29%2Ax\"
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\n" ); document.write( " \"-1%2Ax%2B2%2F3-%281%2F3%29%2Ax=1\" Multiply
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\n" ); document.write( " \"-1%2Ax%2B2%2F3-%281%2F3%29%2Ax=1\" Reduce any fractions
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\n" ); document.write( " \"-1%2Ax-%281%2F3%29%2Ax=1-2%2F3\" Subtract \"2%2F3\" from both sides
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\n" ); document.write( " \"-1%2Ax-%281%2F3%29%2Ax=3%2F3-2%2F3\" Make 1 into a fraction with a denominator of 3
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\n" ); document.write( " \"-1%2Ax-%281%2F3%29%2Ax=1%2F3\" Combine the terms on the right side
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\n" ); document.write( " \"%28-3%2F3%29%2Ax-%281%2F3%29x=1%2F3\" Make -1 into a fraction with a denominator of 3
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\n" ); document.write( " \"%28-4%2F3%29%2Ax=1%2F3\" Now combine the terms on the left side.
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\n" ); document.write( " \"cross%28%283%2F-4%29%28-4%2F3%29%29x=%281%2F3%29%283%2F-4%29\" Multiply both sides by \"3%2F-4\". This will cancel out \"-4%2F3\" and isolate x
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\n" ); document.write( " So when we multiply \"1%2F3\" and \"3%2F-4\" (and simplify) we get
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\n" ); document.write( " \"x=-1%2F4\" <---------------------------------One answer
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\n" ); document.write( " Now that we know that \"x=-1%2F4\", lets substitute that in for x to solve for y
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\n" ); document.write( " \"-1%28-1%2F4%29%2B1%2Ay=1\" Plug in \"x=-1%2F4\" into the 2nd equation
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\n" ); document.write( " \"1%2F4%2B1%2Ay=1\" Multiply
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\n" ); document.write( " \"1%2Ay=1-1%2F4\"Subtract \"1%2F4\" from both sides
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\n" ); document.write( " \"1%2Ay=4%2F4-1%2F4\" Make 1 into a fraction with a denominator of 4
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\n" ); document.write( " \"1%2Ay=3%2F4\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F1%29%281%29%29%2Ay=%283%2F4%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=3%2F4\" Multiply the terms on the right side
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\n" ); document.write( " \"y=3%2F4\" Reduce
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\n" ); document.write( " So this is the other answer
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\n" ); document.write( " \"y=3%2F4\"<---------------------------------Other answer
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\n" ); document.write( " So our solution is
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\n" ); document.write( " \"x=-1%2F4\" and \"y=3%2F4\"
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\n" ); document.write( " which can also look like
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\n" ); document.write( " (\"-1%2F4\",\"3%2F4\")
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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%2B3%2Ay=2\"
\n" ); document.write( " \"-1%2Ax%2B1%2Ay=1\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"1%2Ax%2B3%2Ay=2\" (red) and \"-1%2Ax%2B1%2Ay=1\" (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%2F4\",\"3%2F4\"). This verifies our answer.
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\n" ); document.write( " Check:
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\n" ); document.write( " Plug in (\"-1%2F4\",\"3%2F4\") into the system of equations
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\n" ); document.write( " Let \"x=-1%2F4\" and \"y=3%2F4\". Now plug those values into the equation \"1%2Ax%2B3%2Ay=2\"
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\n" ); document.write( " \"1%2A%28-1%2F4%29%2B3%2A%283%2F4%29=2\" Plug in \"x=-1%2F4\" and \"y=3%2F4\"
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\n" ); document.write( " \"-1%2F4%2B9%2F4=2\" Multiply
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\n" ); document.write( " \"8%2F4=2\" Add
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\n" ); document.write( " \"2=2\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"-1%2F4\",\"3%2F4\") satisfies \"1%2Ax%2B3%2Ay=2\"
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\n" ); document.write( " Let \"x=-1%2F4\" and \"y=3%2F4\". Now plug those values into the equation \"-1%2Ax%2B1%2Ay=1\"
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\n" ); document.write( " \"-1%2A%28-1%2F4%29%2B1%2A%283%2F4%29=1\" Plug in \"x=-1%2F4\" and \"y=3%2F4\"
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\n" ); document.write( " \"1%2F4%2B3%2F4=1\" Multiply
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\n" ); document.write( " \"4%2F4=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%2F4\",\"3%2F4\") satisfies \"-1%2Ax%2B1%2Ay=1\"
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\n" ); document.write( " Since the solution (\"-1%2F4\",\"3%2F4\") satisfies the system of equations
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\n" ); document.write( " \"1%2Ax%2B3%2Ay=2\"
\n" ); document.write( " \"-1%2Ax%2B1%2Ay=1\"
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\n" ); document.write( " this verifies our answer.
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