document.write( "Question 110098: please help me solve by substitution:
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Algebra.Com's Answer #80209 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( " \"4%2Ax%2B3%2Ay=-3\"
\n" ); document.write( " \"1%2Ax%2B1%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( " \"3%2Ay=-3-4%2Ax\"Subtract \"4%2Ax\" from both sides
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\n" ); document.write( " \"y=%28-3-4%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=-1-%284%2F3%29%2Ax\" Now we've fully isolated y
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\n" ); document.write( " Since y equals \"-1-%284%2F3%29%2Ax\" we can substitute the expression \"-1-%284%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%28-1-%284%2F3%29%2Ax%29%29=-3\" Replace y with \"-1-%284%2F3%29%2Ax\". Since this eliminates y, we can now solve for x.
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\n" ); document.write( " \"1%2Ax%2B1%2A%28-1%29%2B1%28-4%2F3%29x=-3\" Distribute 1 to \"-1-%284%2F3%29%2Ax\"
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\n" ); document.write( " \"1%2Ax-1-%284%2F3%29%2Ax=-3\" Multiply
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\n" ); document.write( " \"1%2Ax-1-%284%2F3%29%2Ax=-3\" Reduce any fractions
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\n" ); document.write( " \"1%2Ax-%284%2F3%29%2Ax=-3%2B1\"Add \"1\" to both sides
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\n" ); document.write( " \"1%2Ax-%284%2F3%29%2Ax=-2\" Combine the terms on the right side
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\n" ); document.write( " \"%283%2F3%29%2Ax-%284%2F3%29x=-2\" Make 1 into a fraction with a denominator of 3
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\n" ); document.write( " \"%28-1%2F3%29%2Ax=-2\" Now combine the terms on the left side.
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\n" ); document.write( " \"cross%28%283%2F-1%29%28-1%2F3%29%29x=%28-2%2F1%29%283%2F-1%29\" Multiply both sides by \"3%2F-1\". This will cancel out \"-1%2F3\" and isolate x
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\n" ); document.write( " So when we multiply \"-2%2F1\" and \"3%2F-1\" (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%2B1%2Ay=-3\" Plug in \"x=6\" into the 2nd equation
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\n" ); document.write( " \"6%2B1%2Ay=-3\" Multiply
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\n" ); document.write( " \"1%2Ay=-3-6\"Subtract \"6\" from both sides
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\n" ); document.write( " \"1%2Ay=-9\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F1%29%281%29%29%2Ay=%28-9%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=-9%2F1\" Multiply the terms on the right side
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\n" ); document.write( " \"y=-9\" Reduce
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\n" ); document.write( " So this is the other answer
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\n" ); document.write( " \"y=-9\"<---------------------------------Other answer
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\n" ); document.write( " So our solution is
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\n" ); document.write( " \"x=6\" and \"y=-9\"
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\n" ); document.write( " which can also look like
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\n" ); document.write( " (\"6\",\"-9\")
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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( " \"4%2Ax%2B3%2Ay=-3\"
\n" ); document.write( " \"1%2Ax%2B1%2Ay=-3\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"4%2Ax%2B3%2Ay=-3\" (red) and \"1%2Ax%2B1%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 (\"6\",\"-9\"). This verifies our answer.
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\n" ); document.write( " Check:
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\n" ); document.write( " Plug in (\"6\",\"-9\") into the system of equations
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\n" ); document.write( " Let \"x=6\" and \"y=-9\". Now plug those values into the equation \"4%2Ax%2B3%2Ay=-3\"
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\n" ); document.write( " \"4%2A%286%29%2B3%2A%28-9%29=-3\" Plug in \"x=6\" and \"y=-9\"
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\n" ); document.write( " \"24-27=-3\" Multiply
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\n" ); document.write( " \"-3=-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 (\"6\",\"-9\") satisfies \"4%2Ax%2B3%2Ay=-3\"
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\n" ); document.write( "
\n" ); document.write( " Let \"x=6\" and \"y=-9\". Now plug those values into the equation \"1%2Ax%2B1%2Ay=-3\"
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\n" ); document.write( " \"1%2A%286%29%2B1%2A%28-9%29=-3\" Plug in \"x=6\" and \"y=-9\"
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\n" ); document.write( " \"6-9=-3\" Multiply
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\n" ); document.write( " \"-3=-3\" Add
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\n" ); document.write( "
\n" ); document.write( " \"-3=-3\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"6\",\"-9\") satisfies \"1%2Ax%2B1%2Ay=-3\"
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\n" ); document.write( " Since the solution (\"6\",\"-9\") satisfies the system of equations
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\n" ); document.write( " \"4%2Ax%2B3%2Ay=-3\"
\n" ); document.write( " \"1%2Ax%2B1%2Ay=-3\"
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\n" ); document.write( " this verifies our answer.
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