document.write( "Question 701656: What is the x-coordinate of the point of intersection for two lines below?
\n" ); document.write( "X-2y=-2
\n" ); document.write( "Y=-6x+40
\n" ); document.write( "A, -82\13
\n" ); document.write( "B,-42/13
\n" ); document.write( "C, 6
\n" ); document.write( "D, 7
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Algebra.Com's Answer #432506 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( " \"6%2Ax%2B1%2Ay=40\"
\n" ); document.write( " \"1%2Ax-2%2Ay=-2\"
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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=40-6%2Ax\"Subtract \"6%2Ax\" from both sides
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\n" ); document.write( " \"y=%2840-6%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=40-6%2Ax\" Now we've fully isolated y
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\n" ); document.write( " Since y equals \"40-6%2Ax\" we can substitute the expression \"40-6%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-2%2Ahighlight%28%2840-6%2Ax%29%29=-2\" Replace y with \"40-6%2Ax\". Since this eliminates y, we can now solve for x.
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\n" ); document.write( " \"1%2Ax-2%2A%2840%29-2%28-6%29x=-2\" Distribute -2 to \"40-6%2Ax\"
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\n" ); document.write( " \"1%2Ax-80%2B12%2Ax=-2\" Multiply
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\n" ); document.write( " \"1%2Ax-80%2B12%2Ax=-2\" Reduce any fractions
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\n" ); document.write( " \"1%2Ax%2B12%2Ax=-2%2B80\"Add \"80\" to both sides
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\n" ); document.write( " \"1%2Ax%2B12%2Ax=78\" Combine the terms on the right side
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\n" ); document.write( " \"13%2Ax=78\" Now combine the terms on the left side.
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\n" ); document.write( " \"cross%28%281%2F13%29%2813%2F1%29%29x=%2878%2F1%29%281%2F13%29\" Multiply both sides by \"1%2F13\". This will cancel out \"13%2F1\" and isolate x
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\n" ); document.write( " So when we multiply \"78%2F1\" and \"1%2F13\" (and simplify) we get
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\n" ); document.write( " \"x=6\" <---------------------------------One answer
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\n" ); document.write( " Now that we know that \"x=6\", lets substitute that in for x to solve for y
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\n" ); document.write( " \"1%286%29-2%2Ay=-2\" Plug in \"x=6\" into the 2nd equation
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\n" ); document.write( " \"6-2%2Ay=-2\" Multiply
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\n" ); document.write( " \"-2%2Ay=-2-6\"Subtract \"6\" from both sides
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\n" ); document.write( " \"-2%2Ay=-8\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F-2%29%28-2%29%29%2Ay=%28-8%2F1%29%281%2F-2%29\" Multiply both sides by \"1%2F-2\". This will cancel out -2 on the left side.
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\n" ); document.write( " \"y=-8%2F-2\" 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=6\" and \"y=4\"
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\n" ); document.write( " which can also look like
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\n" ); document.write( " (\"6\",\"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( " \"6%2Ax%2B1%2Ay=40\"
\n" ); document.write( " \"1%2Ax-2%2Ay=-2\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"6%2Ax%2B1%2Ay=40\" (red) and \"1%2Ax-2%2Ay=-2\" (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 (\"6\",\"4\"). This verifies our answer.
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\n" ); document.write( " -----------------------------------------------------------------------------------------------
\n" ); document.write( " Check:
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\n" ); document.write( " Plug in (\"6\",\"4\") into the system of equations
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\n" ); document.write( " Let \"x=6\" and \"y=4\". Now plug those values into the equation \"6%2Ax%2B1%2Ay=40\"
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\n" ); document.write( " \"6%2A%286%29%2B1%2A%284%29=40\" Plug in \"x=6\" and \"y=4\"
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\n" ); document.write( " \"36%2B4=40\" Multiply
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\n" ); document.write( " \"40=40\" Add
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\n" ); document.write( " \"40=40\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"6\",\"4\") satisfies \"6%2Ax%2B1%2Ay=40\"
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\n" ); document.write( " Let \"x=6\" and \"y=4\". Now plug those values into the equation \"1%2Ax-2%2Ay=-2\"
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\n" ); document.write( " \"1%2A%286%29-2%2A%284%29=-2\" Plug in \"x=6\" and \"y=4\"
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\n" ); document.write( " \"6-8=-2\" Multiply
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\n" ); document.write( " \"-2=-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 (\"6\",\"4\") satisfies \"1%2Ax-2%2Ay=-2\"
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\n" ); document.write( " Since the solution (\"6\",\"4\") satisfies the system of equations
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\n" ); document.write( " \"6%2Ax%2B1%2Ay=40\"
\n" ); document.write( " \"1%2Ax-2%2Ay=-2\"
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\n" ); document.write( " this verifies our answer.
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