document.write( "Question 992474: PLS HELP.ME ANSWER THIS PLS.. \r
\n" ); document.write( "\n" ); document.write( "Simplify the following Linear Equation.
\n" ); document.write( "Using Elimination,Substition,Determinants and Graphical. \r
\n" ); document.write( "\n" ); document.write( "1) 2x+3y=18
\n" ); document.write( " 4x+6y=12\r
\n" ); document.write( "\n" ); document.write( "2) 4x+y=6
\n" ); document.write( " -8x-2y=21
\n" ); document.write( "
\n" ); document.write( "

Algebra.Com's Answer #612166 by MathLover1(20850)\"\" \"About 
You can put this solution on YOUR website!
Using: \r
\n" ); document.write( "\n" ); document.write( "\"highlight%28Elimination%29\" \r
\n" ); document.write( "\n" ); document.write( "1) \"2x%2B3y=18\"
\n" ); document.write( " \"4x%2B6y=12\"\r
\n" ); document.write( "\n" ); document.write( "\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "\n" ); document.write( "
Solved by pluggable solver: Solving a System of Linear Equations by Elimination/Addition

\n" ); document.write( "
\n" ); document.write( " Lets start with the given system of linear equations
\n" ); document.write( "
\n" ); document.write( " \"2%2Ax%2B3%2Ay=18\"
\n" ); document.write( " \"4%2Ax%2B6%2Ay=12\"
\n" ); document.write( "
\n" ); document.write( " In order to solve for one variable, we must eliminate the other variable. So if we wanted to solve for y, we would have to eliminate x (or vice versa).
\n" ); document.write( "
\n" ); document.write( " So lets eliminate x. In order to do that, we need to have both x coefficients that are equal but have opposite signs (for instance 2 and -2 are equal but have opposite signs). This way they will add to zero.
\n" ); document.write( "
\n" ); document.write( " So to make the x coefficients equal but opposite, we need to multiply both x coefficients by some number to get them to an equal number. So if we wanted to get 2 and 4 to some equal number, we could try to get them to the LCM.
\n" ); document.write( "
\n" ); document.write( " Since the LCM of 2 and 4 is 4, we need to multiply both sides of the top equation by 2 and multiply both sides of the bottom equation by -1 like this:
\n" ); document.write( "
\n" ); document.write( " \"2%2A%282%2Ax%2B3%2Ay%29=%2818%29%2A2\" Multiply the top equation (both sides) by 2
\n" ); document.write( " \"-1%2A%284%2Ax%2B6%2Ay%29=%2812%29%2A-1\" Multiply the bottom equation (both sides) by -1
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " So after multiplying we get this:
\n" ); document.write( " \"4%2Ax%2B6%2Ay=36\"
\n" ); document.write( " \"-4%2Ax-6%2Ay=-12\"
\n" ); document.write( "
\n" ); document.write( " Notice how 4 and -4 and 36 and -6 add to zero (ie \"4%2B-4=0\" \"6%2B-6=0\")
\n" ); document.write( "
\n" ); document.write( " However 36 and -12 add to 24 (ie \"36%2B-12=24\");
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " So we're left with
\n" ); document.write( "
\n" ); document.write( " \"0=24\"
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\n" ); document.write( "
\n" ); document.write( " which means no value of x or y value will satisfy the system of equations. So there are no solutions
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " So this system is inconsistent
\n" ); document.write( " \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "2) \"4x%2By=6\"
\n" ); document.write( " \"-8x-2y=21\"\r
\n" ); document.write( "\n" ); document.write( "\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "\n" ); document.write( "
Solved by pluggable solver: Solving a System of Linear Equations by Elimination/Addition

\n" ); document.write( "
\n" ); document.write( " Lets start with the given system of linear equations
\n" ); document.write( "
\n" ); document.write( " \"4%2Ax%2B1%2Ay=6\"
\n" ); document.write( " \"-8%2Ax-2%2Ay=21\"
\n" ); document.write( "
\n" ); document.write( " In order to solve for one variable, we must eliminate the other variable. So if we wanted to solve for y, we would have to eliminate x (or vice versa).
\n" ); document.write( "
\n" ); document.write( " So lets eliminate x. In order to do that, we need to have both x coefficients that are equal but have opposite signs (for instance 2 and -2 are equal but have opposite signs). This way they will add to zero.
\n" ); document.write( "
\n" ); document.write( " So to make the x coefficients equal but opposite, we need to multiply both x coefficients by some number to get them to an equal number. So if we wanted to get 4 and -8 to some equal number, we could try to get them to the LCM.
\n" ); document.write( "
\n" ); document.write( " Since the LCM of 4 and -8 is -8, we need to multiply both sides of the top equation by -2 and multiply both sides of the bottom equation by -1 like this:
\n" ); document.write( "
\n" ); document.write( " \"-2%2A%284%2Ax%2B1%2Ay%29=%286%29%2A-2\" Multiply the top equation (both sides) by -2
\n" ); document.write( " \"-1%2A%28-8%2Ax-2%2Ay%29=%2821%29%2A-1\" Multiply the bottom equation (both sides) by -1
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " So after multiplying we get this:
\n" ); document.write( " \"-8%2Ax-2%2Ay=-12\"
\n" ); document.write( " \"8%2Ax%2B2%2Ay=-21\"
\n" ); document.write( "
\n" ); document.write( " Notice how -8 and 8 and -12 and 2 add to zero (ie \"-8%2B8=0\" \"-2%2B2=0\")
\n" ); document.write( "
\n" ); document.write( " However -12 and -21 add to -33 (ie \"-12%2B-21=-33\");
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " So we're left with
\n" ); document.write( "
\n" ); document.write( " \"0=-33\"
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " which means no value of x or y value will satisfy the system of equations. So there are no solutions
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " So this system is inconsistent
\n" ); document.write( "
\n" ); document.write( " \r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"highlight%28Substitution%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "1) \"2x%2B3y=18\"
\n" ); document.write( " \"4x%2B6y=12\"\r
\n" ); document.write( "\n" ); document.write( "\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "\n" ); document.write( "
Solved by pluggable solver: SOLVE linear system by SUBSTITUTION
Solve:
\n" ); document.write( " \"+system%28+%0D%0A++++2%5Cx+%2B+3%5Cy+=+18%2C%0D%0A++++4%5Cx+%2B+6%5Cy+=+12+%29%0D%0A++\"We'll use substitution. After moving 3*y to the right, we get:
\n" ); document.write( " \"2%2Ax+=+18+-+3%2Ay\", or \"x+=+18%2F2+-+3%2Ay%2F2\". Substitute that
\n" ); document.write( " into another equation:
\n" ); document.write( " \"4%2A%2818%2F2+-+3%2Ay%2F2%29+%2B+6%5Cy+=+12\" and simplify: So, we know that y=24=0. Since \"x+=+18%2F2+-+3%2Ay%2F2\", x=-27.
\n" ); document.write( "
\n" ); document.write( " Answer: \"system%28+x=-27%2C+y=24=0+%29\".
\n" ); document.write( "

\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "2) \"4x%2By=6\"
\n" ); document.write( " \"-8x-2y=21\"\r
\n" ); document.write( "\n" ); document.write( "\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "\n" ); document.write( "
Solved by pluggable solver: SOLVE linear system by SUBSTITUTION
Solve:
\n" ); document.write( " \"+system%28+%0D%0A++++4%5Cx+%2B+1%5Cy+=+6%2C%0D%0A++++-8%5Cx+%2B+-2%5Cy+=+21+%29%0D%0A++\"We'll use substitution. After moving 1*y to the right, we get:
\n" ); document.write( " \"4%2Ax+=+6+-+1%2Ay\", or \"x+=+6%2F4+-+1%2Ay%2F4\". Substitute that
\n" ); document.write( " into another equation:
\n" ); document.write( " \"-8%2A%286%2F4+-+1%2Ay%2F4%29+%2B+-2%5Cy+=+21\" and simplify: So, we know that y=-33=0. Since \"x+=+6%2F4+-+1%2Ay%2F4\", x=9.75.
\n" ); document.write( "
\n" ); document.write( " Answer: \"system%28+x=9.75%2C+y=-33=0+%29\".
\n" ); document.write( "

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\n" ); document.write( "\n" ); document.write( "\"highlight%28Determinants+%29\"\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "1) \"2x%2B3y=18\"
\n" ); document.write( " \"4x%2B6y=12\"\r
\n" ); document.write( "\n" ); document.write( "\"2\" by \"2\" systems of linear equations are of the form\r
\n" ); document.write( "\n" ); document.write( "\"a+x+%2B+b+y+=+c\"\r
\n" ); document.write( "\n" ); document.write( " and \"y+=+%28a+f+-+d+c%29+%2F+D\" where \"D\" is the coefficient determinant given by \"D+=+a+e+-+b+d\". \r
\n" ); document.write( "\n" ); document.write( "in your case \"a=2\",\"b=3\",\"c=18\",\"d=4\",\"e=6\",and \"f=12\"\r
\n" ); document.write( "\n" ); document.write( "then you have:\r
\n" ); document.write( "\n" ); document.write( "determinant \"D+=+a+e+-+b+d\"=>\"D+=+2%2A6+-3%2A+4\"=>\"D+=+12+-12\"=>\"D+=+0\"\r
\n" ); document.write( "\n" ); document.write( "since determinant equal to zero, this system has no solution\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "2) \"4x%2By=6\"
\n" ); document.write( " \"-8x-2y=21\"\r
\n" ); document.write( "\n" ); document.write( "in this case \"a=4\",\"b=1\",\"c=6\",\"d=-8\",\"e=-2\",and \"f=21\"\r
\n" ); document.write( "\n" ); document.write( "then you have:\r
\n" ); document.write( "\n" ); document.write( "determinant \"D+=+a+e+-+b+d\"=>\"D+=+4%28-2%29+-+1%28-8%29\"=>\"D+=-8+-+%28-8%29\"=>
\n" ); document.write( "\"D+=-8%2B8\"=>\"D+=0\"\r
\n" ); document.write( "\n" ); document.write( "so, determinant equal to zero, this system has no solution\r
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "\"highlight%28Graphical%29\"\r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "1) \"2x%2B3y=18\"
\n" ); document.write( " \"4x%2B6y=12\"\r
\n" ); document.write( "\n" ); document.write( "\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "\n" ); document.write( "
Solved by pluggable solver: Solve the System of Equations by Graphing

\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " Start with the given system of equations:
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"2x%2B3y=18\"
\n" ); document.write( "
\n" ); document.write( " \"4x%2B6y=12\"
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " In order to graph these equations, we need to solve for y for each equation.
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " So let's solve for y on the first equation
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"2x%2B3y=18\" Start with the given equation
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"3y=18-2x\" Subtract \"2+x\" from both sides
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"3y=-2x%2B18\" Rearrange the equation
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"y=%28-2x%2B18%29%2F%283%29\" Divide both sides by \"3\"
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"y=%28-2%2F3%29x%2B%2818%29%2F%283%29\" Break up the fraction
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"y=%28-2%2F3%29x%2B6\" Reduce
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " Now lets graph \"y=%28-2%2F3%29x%2B6\" (note: if you need help with graphing, check out this solver)
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+%28-2%2F3%29x%2B6%29+\" Graph of \"y=%28-2%2F3%29x%2B6\"
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " So let's solve for y on the second equation
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"4x%2B6y=12\" Start with the given equation
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"6y=12-4x\" Subtract \"4+x\" from both sides
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"6y=-4x%2B12\" Rearrange the equation
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"y=%28-4x%2B12%29%2F%286%29\" Divide both sides by \"6\"
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"y=%28-4%2F6%29x%2B%2812%29%2F%286%29\" Break up the fraction
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"y=%28-2%2F3%29x%2B2\" Reduce
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " Now lets add the graph of \"y=%28-2%2F3%29x%2B2\" to our first plot to get:
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+%28-2%2F3%29x%2B6%2C%28-2%2F3%29x%2B2%29+\" Graph of \"y=%28-2%2F3%29x%2B6\"(red) and \"y=%28-2%2F3%29x%2B2\"(green)
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " From the graph, we can see that the two lines are parallel and will never intersect. So there are no solutions and the system is inconsistent.
\n" ); document.write( " \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "2) \"4x%2By=6\"
\n" ); document.write( " \"-8x-2y=21\"\r
\n" ); document.write( "\n" ); document.write( "\n" ); document.write( "\n" ); document.write( " \n" ); document.write( "\n" ); document.write( "
Solved by pluggable solver: Solve the System of Equations by Graphing

\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " Start with the given system of equations:
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"4x%2By=6\"
\n" ); document.write( "
\n" ); document.write( " \"-8x-2y=21\"
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " In order to graph these equations, we need to solve for y for each equation.
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " So let's solve for y on the first equation
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"4x%2By=6\" Start with the given equation
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"1y=6-4x\" Subtract \"4+x\" from both sides
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"1y=-4x%2B6\" Rearrange the equation
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"y=%28-4x%2B6%29%2F%281%29\" Divide both sides by \"1\"
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"y=%28-4%2F1%29x%2B%286%29%2F%281%29\" Break up the fraction
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"y=-4x%2B6\" Reduce
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " Now lets graph \"y=-4x%2B6\" (note: if you need help with graphing, check out this solver)
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+-4x%2B6%29+\" Graph of \"y=-4x%2B6\"
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " So let's solve for y on the second equation
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"-8x-2y=21\" Start with the given equation
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"-2y=21%2B8x\" Add \"8+x\" to both sides
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"-2y=%2B8x%2B21\" Rearrange the equation
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"y=%28%2B8x%2B21%29%2F%28-2%29\" Divide both sides by \"-2\"
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"y=%28%2B8%2F-2%29x%2B%2821%29%2F%28-2%29\" Break up the fraction
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"y=-4x-21%2F2\" Reduce
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " Now lets add the graph of \"y=-4x-21%2F2\" to our first plot to get:
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " \"+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+-4x%2B6%2C-4x-21%2F2%29+\" Graph of \"y=-4x%2B6\"(red) and \"y=-4x-21%2F2\"(green)
\n" ); document.write( "
\n" ); document.write( "
\n" ); document.write( " From the graph, we can see that the two lines are parallel and will never intersect. So there are no solutions and the system is inconsistent.
\n" ); document.write( " \r
\n" ); document.write( "
\n" ); document.write( "\n" ); document.write( "
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