document.write( "Question 705217: x+2y=54
\n" ); document.write( "x+5y=110\r
\n" ); document.write( "\n" ); document.write( "Find x and y\r
\n" ); document.write( "\n" ); document.write( "Haven't done this for 45 years, and have forgotten how!\r
\n" ); document.write( "\n" ); document.write( "Many thanks
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Algebra.Com's Answer #434462 by mouk(232)\"\" \"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%2B2%2Ay=54\"
\n" ); document.write( " \"1%2Ax%2B5%2Ay=110\"
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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( " \"2%2Ay=54-1%2Ax\"Subtract \"1%2Ax\" from both sides
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\n" ); document.write( " \"y=%2854-1%2Ax%29%2F2\" Divide both sides by 2.
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\n" ); document.write( " Which breaks down and reduces to
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\n" ); document.write( " \"y=27-%281%2F2%29%2Ax\" Now we've fully isolated y
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\n" ); document.write( " Since y equals \"27-%281%2F2%29%2Ax\" we can substitute the expression \"27-%281%2F2%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%2B5%2Ahighlight%28%2827-%281%2F2%29%2Ax%29%29=110\" Replace y with \"27-%281%2F2%29%2Ax\". Since this eliminates y, we can now solve for x.
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\n" ); document.write( " \"1%2Ax%2B5%2A%2827%29%2B5%28-1%2F2%29x=110\" Distribute 5 to \"27-%281%2F2%29%2Ax\"
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\n" ); document.write( " \"1%2Ax%2B135-%285%2F2%29%2Ax=110\" Multiply
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\n" ); document.write( " \"1%2Ax%2B135-%285%2F2%29%2Ax=110\" Reduce any fractions
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\n" ); document.write( " \"1%2Ax-%285%2F2%29%2Ax=110-135\" Subtract \"135\" from both sides
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\n" ); document.write( " \"1%2Ax-%285%2F2%29%2Ax=-25\" Combine the terms on the right side
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\n" ); document.write( " \"%282%2F2%29%2Ax-%285%2F2%29x=-25\" Make 1 into a fraction with a denominator of 2
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\n" ); document.write( " \"%28-3%2F2%29%2Ax=-25\" Now combine the terms on the left side.
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\n" ); document.write( " \"cross%28%282%2F-3%29%28-3%2F2%29%29x=%28-25%2F1%29%282%2F-3%29\" Multiply both sides by \"2%2F-3\". This will cancel out \"-3%2F2\" and isolate x
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\n" ); document.write( " So when we multiply \"-25%2F1\" and \"2%2F-3\" (and simplify) we get
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\n" ); document.write( " \"x=50%2F3\" <---------------------------------One answer
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\n" ); document.write( " Now that we know that \"x=50%2F3\", lets substitute that in for x to solve for y
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\n" ); document.write( " \"1%2850%2F3%29%2B5%2Ay=110\" Plug in \"x=50%2F3\" into the 2nd equation
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\n" ); document.write( " \"50%2F3%2B5%2Ay=110\" Multiply
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\n" ); document.write( " \"5%2Ay=110-50%2F3\"Subtract \"50%2F3\" from both sides
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\n" ); document.write( " \"5%2Ay=330%2F3-50%2F3\" Make 110 into a fraction with a denominator of 3
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\n" ); document.write( " \"5%2Ay=280%2F3\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F5%29%285%29%29%2Ay=%28280%2F3%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( " \"y=280%2F15\" Multiply the terms on the right side
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\n" ); document.write( " \"y=56%2F3\" Reduce
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\n" ); document.write( " So this is the other answer
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\n" ); document.write( " \"y=56%2F3\"<---------------------------------Other answer
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\n" ); document.write( " So our solution is
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\n" ); document.write( " \"x=50%2F3\" and \"y=56%2F3\"
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\n" ); document.write( " which can also look like
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\n" ); document.write( " (\"50%2F3\",\"56%2F3\")
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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%2B2%2Ay=54\"
\n" ); document.write( " \"1%2Ax%2B5%2Ay=110\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"1%2Ax%2B2%2Ay=54\" (red) and \"1%2Ax%2B5%2Ay=110\" (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 (\"50%2F3\",\"56%2F3\"). This verifies our answer.
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\n" ); document.write( " Check:
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\n" ); document.write( " Plug in (\"50%2F3\",\"56%2F3\") into the system of equations
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\n" ); document.write( " Let \"x=50%2F3\" and \"y=56%2F3\". Now plug those values into the equation \"1%2Ax%2B2%2Ay=54\"
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\n" ); document.write( " \"1%2A%2850%2F3%29%2B2%2A%2856%2F3%29=54\" Plug in \"x=50%2F3\" and \"y=56%2F3\"
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\n" ); document.write( " \"50%2F3%2B112%2F3=54\" Multiply
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\n" ); document.write( " \"162%2F3=54\" Add
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\n" ); document.write( " \"54=54\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"50%2F3\",\"56%2F3\") satisfies \"1%2Ax%2B2%2Ay=54\"
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\n" ); document.write( " Let \"x=50%2F3\" and \"y=56%2F3\". Now plug those values into the equation \"1%2Ax%2B5%2Ay=110\"
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\n" ); document.write( " \"1%2A%2850%2F3%29%2B5%2A%2856%2F3%29=110\" Plug in \"x=50%2F3\" and \"y=56%2F3\"
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\n" ); document.write( " \"50%2F3%2B280%2F3=110\" Multiply
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\n" ); document.write( " \"330%2F3=110\" Add
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\n" ); document.write( " \"110=110\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"50%2F3\",\"56%2F3\") satisfies \"1%2Ax%2B5%2Ay=110\"
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\n" ); document.write( " Since the solution (\"50%2F3\",\"56%2F3\") satisfies the system of equations
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\n" ); document.write( " \"1%2Ax%2B2%2Ay=54\"
\n" ); document.write( " \"1%2Ax%2B5%2Ay=110\"
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\n" ); document.write( " this verifies our answer.
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