document.write( "Question 100795This question is from textbook Intro Alg
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\n" ); document.write( "\n" ); document.write( "-4x+y= -11
\n" ); document.write( "2x-3y= 5\r
\n" ); document.write( "\n" ); document.write( "I started by isolating \"x\" in 2nd equation: 2x = 3y+5. I substituted the \"x\" in the 1st equation: -4(3y+5)+y+ -11 to get: -12y-20+y= -11.
\n" ); document.write( "I combined like terms to get: -11y = 9 , to get the solution for \"y\" - 9/11. Is this correct? If so, how do I get \"x\" solution?
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Algebra.Com's Answer #73395 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%2B1%2Ay=-11\"
\n" ); document.write( " \"2%2Ax-3%2Ay=5\"
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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=-11%2B4%2Ax\"Add \"4%2Ax\" to both sides
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\n" ); document.write( " \"y=%28-11%2B4%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=-11%2B4%2Ax\" Now we've fully isolated y
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\n" ); document.write( " Since y equals \"-11%2B4%2Ax\" we can substitute the expression \"-11%2B4%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%2B-3%2Ahighlight%28%28-11%2B4%2Ax%29%29=5\" Replace y with \"-11%2B4%2Ax\". Since this eliminates y, we can now solve for x.
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\n" ); document.write( " \"2%2Ax-3%2A%28-11%29-3%284%29x=5\" Distribute -3 to \"-11%2B4%2Ax\"
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\n" ); document.write( " \"2%2Ax%2B33-12%2Ax=5\" Multiply
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\n" ); document.write( " \"2%2Ax%2B33-12%2Ax=5\" Reduce any fractions
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\n" ); document.write( " \"2%2Ax-12%2Ax=5-33\" Subtract \"33\" from both sides
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\n" ); document.write( " \"2%2Ax-12%2Ax=-28\" Combine the terms on the right side
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\n" ); document.write( " \"-10%2Ax=-28\" Now combine the terms on the left side.
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\n" ); document.write( " \"cross%28%281%2F-10%29%28-10%2F1%29%29x=%28-28%2F1%29%281%2F-10%29\" Multiply both sides by \"1%2F-10\". This will cancel out \"-10%2F1\" and isolate x
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\n" ); document.write( " So when we multiply \"-28%2F1\" and \"1%2F-10\" (and simplify) we get
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\n" ); document.write( " \"x=14%2F5\" <---------------------------------One answer
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\n" ); document.write( " Now that we know that \"x=14%2F5\", lets substitute that in for x to solve for y
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\n" ); document.write( " \"2%2814%2F5%29-3%2Ay=5\" Plug in \"x=14%2F5\" into the 2nd equation
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\n" ); document.write( " \"28%2F5-3%2Ay=5\" Multiply
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\n" ); document.write( " \"-3%2Ay=5-28%2F5\"Subtract \"28%2F5\" from both sides
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\n" ); document.write( " \"-3%2Ay=25%2F5-28%2F5\" Make 5 into a fraction with a denominator of 5
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\n" ); document.write( " \"-3%2Ay=-3%2F5\" Combine the terms on the right side
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\n" ); document.write( " \"cross%28%281%2F-3%29%28-3%29%29%2Ay=%28-3%2F5%29%281%2F-3%29\" Multiply both sides by \"1%2F-3\". This will cancel out -3 on the left side.
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\n" ); document.write( " \"y=-3%2F-15\" Multiply the terms on the right side
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\n" ); document.write( " \"y=1%2F5\" Reduce
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\n" ); document.write( " So this is the other answer
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\n" ); document.write( " \"y=1%2F5\"<---------------------------------Other answer
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\n" ); document.write( " So our solution is
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\n" ); document.write( " \"x=14%2F5\" and \"y=1%2F5\"
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\n" ); document.write( " which can also look like
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\n" ); document.write( " (\"14%2F5\",\"1%2F5\")
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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%2B1%2Ay=-11\"
\n" ); document.write( " \"2%2Ax-3%2Ay=5\"
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\n" ); document.write( " we get
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\n" ); document.write( " graph of \"-4%2Ax%2B1%2Ay=-11\" (red) and \"2%2Ax-3%2Ay=5\" (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 (\"14%2F5\",\"1%2F5\"). This verifies our answer.
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\n" ); document.write( " Check:
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\n" ); document.write( " Plug in (\"14%2F5\",\"1%2F5\") into the system of equations
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\n" ); document.write( " Let \"x=14%2F5\" and \"y=1%2F5\". Now plug those values into the equation \"-4%2Ax%2B1%2Ay=-11\"
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\n" ); document.write( " \"-4%2A%2814%2F5%29%2B1%2A%281%2F5%29=-11\" Plug in \"x=14%2F5\" and \"y=1%2F5\"
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\n" ); document.write( " \"-56%2F5%2B1%2F5=-11\" Multiply
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\n" ); document.write( " \"-55%2F5=-11\" Add
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\n" ); document.write( " \"-11=-11\" Reduce. Since this equation is true the solution works.
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\n" ); document.write( " So the solution (\"14%2F5\",\"1%2F5\") satisfies \"-4%2Ax%2B1%2Ay=-11\"
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\n" ); document.write( " Let \"x=14%2F5\" and \"y=1%2F5\". Now plug those values into the equation \"2%2Ax-3%2Ay=5\"
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\n" ); document.write( " \"2%2A%2814%2F5%29-3%2A%281%2F5%29=5\" Plug in \"x=14%2F5\" and \"y=1%2F5\"
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\n" ); document.write( " \"28%2F5-3%2F5=5\" Multiply
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\n" ); document.write( " \"25%2F5=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 (\"14%2F5\",\"1%2F5\") satisfies \"2%2Ax-3%2Ay=5\"
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\n" ); document.write( " Since the solution (\"14%2F5\",\"1%2F5\") satisfies the system of equations
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\n" ); document.write( " \"-4%2Ax%2B1%2Ay=-11\"
\n" ); document.write( " \"2%2Ax-3%2Ay=5\"
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\n" ); document.write( " this verifies our answer.
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