document.write( "Question 80296This question is from textbook Algebra I
\n" ); document.write( ": Use substitution to solve each system of equations. If the system does not have exactly one solution, state whether it has no solution or infinitely many solutions.\r
\n" ); document.write( "\n" ); document.write( "0.5x-2y=17
\n" ); document.write( "2x+y=104
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Algebra.Com's Answer #59116 by jim_thompson5910(35256)\"\" \"About 
You can put this solution on YOUR website!
Multiply the 1st equation by 2 to get\r
\n" ); document.write( "\n" ); document.write( "\"x-4y=34\"
\n" ); document.write( "\"2x%2By=104\"\r
\n" ); document.write( "\n" ); document.write( "Now solve the system:\r
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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-4%2Ay=34\"
\n" ); document.write( " \"2%2Ax%2B1%2Ay=104\"
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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( " \"-4%2Ay=34-1%2Ax\"Subtract \"1%2Ax\" from both sides
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\n" ); document.write( " \"y=%2834-1%2Ax%29%2F-4\" Divide both sides by -4.
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\n" ); document.write( " Which breaks down and reduces to
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\n" ); document.write( " \"y=-17%2F2%2B%281%2F4%29%2Ax\" Now we've fully isolated y
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\n" ); document.write( " Since y equals \"-17%2F2%2B%281%2F4%29%2Ax\" we can substitute the expression \"-17%2F2%2B%281%2F4%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( " \"2%2Ax%2B1%2Ahighlight%28%28-17%2F2%2B%281%2F4%29%2Ax%29%29=104\" Replace y with \"-17%2F2%2B%281%2F4%29%2Ax\". Since this eliminates y, we can now solve for x.
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\n" ); document.write( " \"2%2Ax%2B1%2A%28-17%2F2%29%2B1%281%2F4%29x=104\" Distribute 1 to \"-17%2F2%2B%281%2F4%29%2Ax\"
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\n" ); document.write( " \"2%2Ax-17%2F2%2B%281%2F4%29%2Ax=104\" Multiply
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\n" ); document.write( " \"2%2Ax-17%2F2%2B%281%2F4%29%2Ax=104\" Reduce any fractions
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\n" ); document.write( " \"2%2Ax%2B%281%2F4%29%2Ax=104%2B17%2F2\"Add \"17%2F2\" to both sides
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\n" ); document.write( " \"2%2Ax%2B%281%2F4%29%2Ax=208%2F2%2B17%2F2\" Make 104 into a fraction with a denominator of 2
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\n" ); document.write( " \"2%2Ax%2B%281%2F4%29%2Ax=225%2F2\" Combine the terms on the right side
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\n" ); document.write( " \"%288%2F4%29%2Ax%2B%281%2F4%29x=225%2F2\" Make 2 into a fraction with a denominator of 4
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\n" ); document.write( " \"%289%2F4%29%2Ax=225%2F2\" Now combine the terms on the left side.
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\n" ); document.write( " \"cross%28%284%2F9%29%289%2F4%29%29x=%28225%2F2%29%284%2F9%29\" Multiply both sides by \"4%2F9\". This will cancel out \"9%2F4\" and isolate x
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\n" ); document.write( " So when we multiply \"225%2F2\" and \"4%2F9\" (and simplify) we get
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\n" ); document.write( " \"x=50\" <---------------------------------One answer
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\n" ); document.write( " Now that we know that \"x=50\", lets substitute that in for x to solve for y
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\n" ); document.write( " \"2%2850%29%2B1%2Ay=104\" Plug in \"x=50\" into the 2nd equation
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\n" ); document.write( " \"100%2B1%2Ay=104\" Multiply
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\n" ); document.write( " \"1%2Ay=104-100\"Subtract \"100\" 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=50\" and \"y=4\"
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\n" ); document.write( " which can also look like
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\n" ); document.write( " (\"50\",\"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-4%2Ay=34\"
\n" ); document.write( " \"2%2Ax%2B1%2Ay=104\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"1%2Ax-4%2Ay=34\" (red) and \"2%2Ax%2B1%2Ay=104\" (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\",\"4\"). This verifies our answer.
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\n" ); document.write( " Check:
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\n" ); document.write( " Plug in (\"50\",\"4\") into the system of equations
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\n" ); document.write( " Let \"x=50\" and \"y=4\". Now plug those values into the equation \"1%2Ax-4%2Ay=34\"
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\n" ); document.write( " \"1%2A%2850%29-4%2A%284%29=34\" Plug in \"x=50\" and \"y=4\"
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\n" ); document.write( " \"50-16=34\" Multiply
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\n" ); document.write( " \"34=34\" Add
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\n" ); document.write( " \"34=34\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"50\",\"4\") satisfies \"1%2Ax-4%2Ay=34\"
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\n" ); document.write( " Let \"x=50\" and \"y=4\". Now plug those values into the equation \"2%2Ax%2B1%2Ay=104\"
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\n" ); document.write( " \"2%2A%2850%29%2B1%2A%284%29=104\" Plug in \"x=50\" and \"y=4\"
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\n" ); document.write( "
\n" ); document.write( " \"100%2B4=104\" Multiply
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\n" ); document.write( " \"104=104\" Add
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\n" ); document.write( " \"104=104\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"50\",\"4\") satisfies \"2%2Ax%2B1%2Ay=104\"
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\n" ); document.write( " Since the solution (\"50\",\"4\") satisfies the system of equations
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\n" ); document.write( " \"1%2Ax-4%2Ay=34\"
\n" ); document.write( " \"2%2Ax%2B1%2Ay=104\"
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\n" ); document.write( " this verifies our answer.
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