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document.write( "  Lets start with the given system of linear equations
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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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document.write( "  Solve for y for the first equation
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  Subtract  from both sides \n" );
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  Divide both sides by 1. \n" );
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document.write( "  Which breaks down and reduces to
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  Now we've fully isolated y \n" );
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document.write( "  Since y equals
  we can substitute the expression  into y of the 2nd equation. This will eliminate y so we can solve for x. \n" );
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  Replace y with  . Since this eliminates y, we can now solve for x. \n" );
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  Distribute 1 to  \n" );
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  Multiply \n" );
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  Reduce any fractions \n" );
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  Subtract  from both sides \n" );
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  Combine the terms on the right side \n" );
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  Now combine the terms on the left side. \n" );
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  Multiply both sides by  . This will cancel out  and isolate x \n" );
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document.write( "  So when we multiply
  and  (and simplify) we get \n" );
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  <---------------------------------One answer \n" );
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document.write( "   Now that we know that
  , lets substitute that in for x to solve for y \n" );
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  Plug in  into the 2nd equation \n" );
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  Multiply \n" );
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  Subtract  from both sides \n" );
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  Combine the terms on the right side \n" );
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  Multiply both sides by  . This will cancel out 1 on the left side. \n" );
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  Multiply the terms on the right side \n" );
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  Reduce \n" );
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document.write( "  So this is the other answer
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  <---------------------------------Other answer \n" );
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document.write( "  So our solution is
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  and  \n" );
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document.write( "  which can also look like
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document.write( "  (
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document.write( "  Notice if we graph the equations (if you need help with graphing, check out this solver)
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document.write( "  we get
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  graph of  (red) and  (green) (hint: you may have to solve for y to graph these) intersecting at the blue circle. \n" );
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document.write( "  and we can see that the two equations intersect at (
  ,  ). This verifies our answer. \n" );
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document.write( "  Check:
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document.write( "  Plug in (
  ,  ) into the system of equations \n" );
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document.write( "  Let
  and  . Now plug those values into the equation  \n" );
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  Plug in  and  \n" );
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  Multiply \n" );
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  Add \n" );
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  Reduce. Since this equation is true the solution works. \n" );
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document.write( "  So the solution (
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document.write( "  Let
  and  . Now plug those values into the equation  \n" );
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  Plug in  and  \n" );
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  Multiply \n" );
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  Add \n" );
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  Reduce. Since this equation is true the solution works. \n" );
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document.write( "  So the solution (
  ,  ) satisfies  \n" );
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document.write( "  Since the solution (
  ,  ) satisfies the system of equations \n" );
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document.write( "  this verifies our answer.
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