document.write( "Question 91969: Solve the following systems by substitution.
\n" ); document.write( " 5x - 2y=-5
\n" ); document.write( " y- 5x =3
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Algebra.Com's Answer #66810 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-2%2Ay=-5\"
\n" ); document.write( " \"1%2Ax-5%2Ay=3\"
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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=-5-5%2Ax\"Subtract \"5%2Ax\" from both sides
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\n" ); document.write( " \"y=%28-5-5%2Ax%29%2F-2\" 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=5%2F2%2B%285%2F2%29%2Ax\" Now we've fully isolated y
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\n" ); document.write( " Since y equals \"5%2F2%2B%285%2F2%29%2Ax\" we can substitute the expression \"5%2F2%2B%285%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%2B-5%2Ahighlight%28%285%2F2%2B%285%2F2%29%2Ax%29%29=3\" Replace y with \"5%2F2%2B%285%2F2%29%2Ax\". Since this eliminates y, we can now solve for x.
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\n" ); document.write( " \"1%2Ax-5%2A%285%2F2%29-5%285%2F2%29x=3\" Distribute -5 to \"5%2F2%2B%285%2F2%29%2Ax\"
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\n" ); document.write( " \"1%2Ax-25%2F2-%2825%2F2%29%2Ax=3\" Multiply
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\n" ); document.write( " \"1%2Ax-25%2F2-%2825%2F2%29%2Ax=3\" Reduce any fractions
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\n" ); document.write( " \"1%2Ax-%2825%2F2%29%2Ax=3%2B25%2F2\"Add \"25%2F2\" to both sides
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\n" ); document.write( " \"1%2Ax-%2825%2F2%29%2Ax=6%2F2%2B25%2F2\" Make 3 into a fraction with a denominator of 2
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\n" ); document.write( " \"1%2Ax-%2825%2F2%29%2Ax=31%2F2\" Combine the terms on the right side
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\n" ); document.write( " \"%282%2F2%29%2Ax-%2825%2F2%29x=31%2F2\" Make 1 into a fraction with a denominator of 2
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\n" ); document.write( " \"%28-23%2F2%29%2Ax=31%2F2\" Now combine the terms on the left side.
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\n" ); document.write( " \"cross%28%282%2F-23%29%28-23%2F2%29%29x=%2831%2F2%29%282%2F-23%29\" Multiply both sides by \"2%2F-23\". This will cancel out \"-23%2F2\" and isolate x
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\n" ); document.write( " So when we multiply \"31%2F2\" and \"2%2F-23\" (and simplify) we get
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\n" ); document.write( " \"x=-31%2F23\" <---------------------------------One answer
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\n" ); document.write( " Now that we know that \"x=-31%2F23\", lets substitute that in for x to solve for y
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\n" ); document.write( " \"1%28-31%2F23%29-5%2Ay=3\" Plug in \"x=-31%2F23\" into the 2nd equation
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\n" ); document.write( " \"-31%2F23-5%2Ay=3\" Multiply
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\n" ); document.write( " \"-5%2Ay=3%2B31%2F23\"Add \"31%2F23\" to both sides
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\n" ); document.write( " \"-5%2Ay=69%2F23%2B31%2F23\" Make 3 into a fraction with a denominator of 23
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\n" ); document.write( " \"-5%2Ay=100%2F23\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F-5%29%28-5%29%29%2Ay=%28100%2F23%29%281%2F-5%29\" Multiply both sides by \"1%2F-5\". This will cancel out -5 on the left side.
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\n" ); document.write( " \"y=100%2F-115\" Multiply the terms on the right side
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\n" ); document.write( " \"y=-20%2F23\" Reduce
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\n" ); document.write( " So this is the other answer
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\n" ); document.write( " \"y=-20%2F23\"<---------------------------------Other answer
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\n" ); document.write( " So our solution is
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\n" ); document.write( " \"x=-31%2F23\" and \"y=-20%2F23\"
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\n" ); document.write( " which can also look like
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\n" ); document.write( " (\"-31%2F23\",\"-20%2F23\")
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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-2%2Ay=-5\"
\n" ); document.write( " \"1%2Ax-5%2Ay=3\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"5%2Ax-2%2Ay=-5\" (red) and \"1%2Ax-5%2Ay=3\" (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 (\"-31%2F23\",\"-20%2F23\"). This verifies our answer.
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\n" ); document.write( " Check:
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\n" ); document.write( " Plug in (\"-31%2F23\",\"-20%2F23\") into the system of equations
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\n" ); document.write( " Let \"x=-31%2F23\" and \"y=-20%2F23\". Now plug those values into the equation \"5%2Ax-2%2Ay=-5\"
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\n" ); document.write( " \"5%2A%28-31%2F23%29-2%2A%28-20%2F23%29=-5\" Plug in \"x=-31%2F23\" and \"y=-20%2F23\"
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\n" ); document.write( " \"-155%2F23%2B40%2F23=-5\" Multiply
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\n" ); document.write( " \"-115%2F23=-5\" Add
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\n" ); document.write( " \"-5=-5\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"-31%2F23\",\"-20%2F23\") satisfies \"5%2Ax-2%2Ay=-5\"
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\n" ); document.write( " Let \"x=-31%2F23\" and \"y=-20%2F23\". Now plug those values into the equation \"1%2Ax-5%2Ay=3\"
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\n" ); document.write( " \"1%2A%28-31%2F23%29-5%2A%28-20%2F23%29=3\" Plug in \"x=-31%2F23\" and \"y=-20%2F23\"
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\n" ); document.write( " \"-31%2F23%2B100%2F23=3\" Multiply
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\n" ); document.write( " \"69%2F23=3\" Add
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\n" ); document.write( " \"3=3\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"-31%2F23\",\"-20%2F23\") satisfies \"1%2Ax-5%2Ay=3\"
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\n" ); document.write( " Since the solution (\"-31%2F23\",\"-20%2F23\") satisfies the system of equations
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\n" ); document.write( " \"5%2Ax-2%2Ay=-5\"
\n" ); document.write( " \"1%2Ax-5%2Ay=3\"
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\n" ); document.write( " this verifies our answer.
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