document.write( "Question 622962: Not sure if i did this right mind helping me out?
\n" ); document.write( "Solve the system of equations
\n" ); document.write( "{x+y+z=-3
\n" ); document.write( "{x-y+3z=-13
\n" ); document.write( "{4x+4y+4z=-15\r
\n" ); document.write( "\n" ); document.write( "My answer looks like this
\n" ); document.write( "x=-2,y=3,z=-4
\n" ); document.write( "

Algebra.Com's Answer #391755 by math-vortex(648)\"\" \"About 
You can put this solution on YOUR website!
Hi, there--
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\n" ); document.write( "Here is how to check your answer. If you got it right, the values you found for x, y, and z will make every equation in the system true.
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\n" ); document.write( "Just substitute -2 for x, 3 for y, and -4 for z in each equation.\r
\n" ); document.write( "\n" ); document.write( "x+y+z=-3
\n" ); document.write( "(-2)+(3)+(-4)=-3
\n" ); document.write( "-3=-3
\n" ); document.write( "Check!!
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\n" ); document.write( "x-y+3z=-13
\n" ); document.write( "(-2)-(3)+3(-4)=-13
\n" ); document.write( "-2-3-12=-13
\n" ); document.write( "-17=-13
\n" ); document.write( "Oops...Your solution doesn't work in this equation.
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\n" ); document.write( "x=-2,y=3,z=-4
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\n" ); document.write( "We can see that there is a problem with your calculations because the solution must work in every equation.
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\n" ); document.write( "Let's start with the elimination method. Multiply every term in equation {A} by -4.
\n" ); document.write( "{A} x+y+z=-3 ---------------> -4x-4y-4z=12
\n" ); document.write( "{B} x-y+3z=-13
\n" ); document.write( "{C} 4x+4y+4z=-15 -----------> 4x+4y+4z=-15
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\n" ); document.write( "Add equations {A} and {C}
\n" ); document.write( "-4x-4y-4z=12
\n" ); document.write( "4x+4y+4z=-15
\n" ); document.write( ".
\n" ); document.write( "Since the variables all cancel out (-4x+4x=0, etc.) we have
\n" ); document.write( "0=-3
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\n" ); document.write( "This result tells us that these two equations have no points in common. In 2-D, this is analogous to parallel lines. Your system has no single point (x,y,z) solution.
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\n" ); document.write( "Here are some pictures of what solutions to systems of equations with three variables can look like:
\n" ); document.write( "http://www.mathwarehouse.com/algebra/planes/systems/three-variable-equations.php
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\n" ); document.write( "Hope this helps! Feel free to email me if you have questions about this explanation.
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\n" ); document.write( "Ms.Figgy
\n" ); document.write( "math.in.the.vortex@gmail.com\r
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