document.write( "Question 167587This question is from textbook Algebra 2
\n" ); document.write( ": Solve each system of equations:
\n" ); document.write( "x+2y=12
\n" ); document.write( "3y-4z=25
\n" ); document.write( "x+6y+z=20
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Algebra.Com's Answer #123509 by Electrified_Levi(103)\"\" \"About 
You can put this solution on YOUR website!
Hi, Hope I can help
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\n" ); document.write( "Solve each system of equations:
\n" ); document.write( "x+2y=12
\n" ); document.write( "3y-4z=25
\n" ); document.write( "x+6y+z=20
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\n" ); document.write( "There is no fast way to solving these problems, but I will show you, what I believe is the easiest way, how to solve these problems
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\n" ); document.write( "First we have to solve for a variable, we will need to solve for \"y\" in each equation, since they all have a variable \"y\" ( It usually doesn't matter, but in this case it does.
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\n" ); document.write( "First equation, x+2y=12. (solve for \"y\")
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\n" ); document.write( "\"+x%2B2y=12+\", We can solve for \"y\", first we will move the \"x\" to the right side
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\n" ); document.write( "\"+x%2B2y+=12+\" = \"+x-x%2B2y+=12-x+\" = \"+2y++=12+-+x+\", we can rearrange the right side
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\n" ); document.write( "\"+2y++=12+-+x+\" = \"+2y++=+-x%2B12+\", to solve for \"y\" we will divide each side by \"2\"
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\n" ); document.write( "\"+2y++=+-x%2B12+\" = \"+2y%2F2++=+%28-x%2B12%29%2F2+\" = \"+y++=+%28-x%2B12%29%2F2+\"
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\n" ); document.write( "\"+%28-x%2B12%29%2F2+\" is our first answer
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\n" ); document.write( "Second equation solve for \"y\", 3y-4z=25
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\n" ); document.write( "\"+3y-4z=25+\", we need to move (-4z) to the right side
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\n" ); document.write( "\"+3y-4z=25+\" = \"+3y-4z+%2B+4z+=25+%2B+4z+\" = \"+3y+=+25+%2B+4z+\", we can rearrange the right side
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\n" ); document.write( "\"+3y+=+25+%2B+4z+\" = \"+3y+=+4z+%2B+25+\", to solve for \"y\" we will need to divide each side by \"3\"
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\n" ); document.write( "\"+3y+=+4z+%2B+25+\" = \"+3y%2F3+=+%284z+%2B+25%29%2F3+\" = \"+y+=+%284z+%2B+25%29%2F3+\"
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\n" ); document.write( "\"+%284z+%2B+25%29%2F3+\" is your second answer
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\n" ); document.write( "Now let us solve the last equation for \"y\", x+6y+z=20
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\n" ); document.write( "\"+x%2B6y%2Bz=20+\", first we will move the \"z\" to the right side
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\n" ); document.write( "\"+x%2B6y%2Bz=20+\" = \"+x%2B6y%2Bz-z=20-z+\" = \"+x%2B6y=20-z+\", now let's move the \"x\" to the right side
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\n" ); document.write( "\"+x%2B6y=20-z+\" = \"+x-x%2B6y=20-z-x+\", \"+6y=20-z-x+\", let us rearrange the right side
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\n" ); document.write( "\"+6y=20-z-x+\" = \"+6y=+-x+-+z+%2B+20+\", to solve for \"y\", we will divide both sides by \"6\"
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\n" ); document.write( "\"+6y=+-x+-+z+%2B+20+\" = \"+6y%2F6=+%28-x+-+z+%2B+20%29%2F6+\" = \"+y+=+%28-x+-+z+%2B+20%29%2F6+\"
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\n" ); document.write( "\"+%28-x+-+z+%2B+20%29%2F6+\" is our third answer
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\n" ); document.write( "Now let us put all of our answers side by side
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\n" ); document.write( "First, \"+%28-x%2B12%29%2F2+\"
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\n" ); document.write( "Second, \"%284z+%2B+25%29%2F3+\"
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\n" ); document.write( "Third, \"+%28-x+-+z+%2B+20%29%2F6+\"
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\n" ); document.write( "Since all three answers are equal to \"y\" all of them are equal to each other, first we have to have both \"x\" and \"z\" in all equations
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\n" ); document.write( "First, \"+%28-x%2B12%29%2F2+\", this has no \"z's\" so this equation would be \"+%28-x%2B0z%2B12%29%2F2+\"
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\n" ); document.write( "Second, \"%284z+%2B+25%29%2F3+\", this has no \"x's\" so this equation would be \"+%280x+%2B+4z+%2B+25%29%2F3+\"
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\n" ); document.write( "Third, \"+%28-x+-+z+%2B+20%29%2F6+\", this already has both \"x\" and \"z\"
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\n" ); document.write( "Here are the new equations
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\n" ); document.write( "First, \"+%28-x%2B0z%2B12%29%2F2+\"
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\n" ); document.write( "Second, \"%280x+%2B+4z+%2B+25%29%2F3+\"
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\n" ); document.write( "Third, \"+%28-x+-+z+%2B+20%29%2F6+\"
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\n" ); document.write( "All of them equal each other, first we will let the first two equations equal each other
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\n" ); document.write( "\"+%28-x%2B0z%2B12%29%2F2+=+%280x+%2B+4z+%2B+25%29%2F3+\", we will use cross multiplication
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\n" ); document.write( "\"+%28-x%2B0z%2B12%29%2F2+=+%280x+%2B+4z+%2B+25%29%2F3+\" = \"+highlight%28-x%2B0z%2B12%29%2F2+=+%280x+%2B+4z+%2B+25%29%2Fhighlight%283%29+\" = \"+%28-x%2B0z%2B12%29%2Fhighlight%282%29+=+highlight%280x+%2B+4z+%2B+25%29%2F3+\"
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\n" ); document.write( "\"+%28-x%2B0z%2B12%29%283%29+=+%282%29%280x+%2B+4z+%2B+25%29+\", we will rearrange the left side
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\n" ); document.write( "\"+%28-x%2B0z%2B12%29%283%29+=+%282%29%280x+%2B+4z+%2B+25%29+\" = \"+%283%29%28-x%2B0z%2B12%29+=+%282%29%280x+%2B+4z+%2B+25%29+\", now we can use the distribution method to solve even more,
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\n" ); document.write( "\"+%283%29%28-x%2B0z%2B12%29+=+%282%29%280x+%2B+4z+%2B+25%29+\" = = =
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\n" ); document.write( "Don't forget to use the positive, and negative signs
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\n" ); document.write( "\"+-3x+%2B+0z+%2B+36+=+0x+%2B+8z+%2B+50+\", we will move the (-3x) and \"0z\" to the right side
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\n" ); document.write( "\"+-3x+%2B+0z+%2B+36+=+0x+%2B+8z+%2B+50+\" = \"+-3x+%2B+3x+%2B+0z+-0z+%2B+36+=+0x+%2B+3x+%2B+8z+-0z+%2B+50+\" = \"++36+=+3x+%2B+8z+%2B+50+\", now we will move the \"50\" to the left side
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\n" ); document.write( "\"++36+=+3x+%2B+8z+%2B+50+\" = \"++36+-+50+=+3x+%2B+8z+%2B+50+-+50+\" = \"++-14+=+3x+%2B+8z+\", rearranging we get
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\n" ); document.write( "\"++-14+=+3x+%2B+8z+\" = \"++3x+%2B+8z+=+-14+\"
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\n" ); document.write( "\"++3x+%2B+8z+=+-14+\" is our first answer
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\n" ); document.write( "Now we can use the last two equations ( we can use the middle equation twice
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\n" ); document.write( "Second, \"%280x+%2B+4z+%2B+25%29%2F3+\"
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\n" ); document.write( "Third, \"+%28-x+-+z+%2B+20%29%2F6+\"
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\n" ); document.write( " \"+%280x+%2B+4z+%2B+25%29%2F3+=+%28-x+-+z+%2B+20%29%2F6+\", we can use cross multiplication
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\n" ); document.write( "\"+%280x+%2B+4z+%2B+25%29%2F3+=+%28-x+-+z+%2B+20%29%2F6+\" = \"+highlight%280x+%2B+4z+%2B+25%29%2F3+=+%28-x+-+z+%2B+20%29%2Fhighlight%286%29+\" = \"+%280x+%2B+4z+%2B+25%29%2Fhighlight%283%29+=+highlight%28-x+-+z+%2B+20%29%2F6+\"
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\n" ); document.write( "\"+%280x+%2B+4z+%2B+25%29%286%29+=+%283%29%28-x-z%2B20%29+\", rearranging the left side
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\n" ); document.write( "\"+%280x+%2B+4z+%2B+25%29%286%29+=+%283%29%28-x-z%2B20%29+\" = \"+%286%29%280x+%2B+4z+%2B+25%29+=+%283%29%28-x-z%2B20%29+\", we will use the distrubution method,
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\n" ); document.write( " = =
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\n" ); document.write( "Remember the signs, \"+0x+%2B+24z+%2B+150+=+-3x-3z%2B60+\", we will move \"-3x\" to the left side
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\n" ); document.write( "\"+0x+%2B+24z+%2B+150+=+-3x-3z%2B60+\" = \"+0x%2B3x+%2B+24z+%2B+150+=+-3x%2B3x-3z%2B60+\" = \"+3x+%2B+24z+%2B+150+=+-3z%2B60+\", we will now move \"-3z to the left side
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\n" ); document.write( "\"+3x+%2B+24z+%2B+150+=+-3z%2B60+\" = \"+3x+%2B+24z%2B3z+%2B+150+=+-3z%2B3z%2B60+\" = \"+3x+%2B+27z+%2B+150+=+60+\", we will lastly move \"150\" to the right side
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\n" ); document.write( "\"+3x+%2B+27z+%2B+150+=+60+\" = \"+3x+%2B+27z+%2B+150+-+150++=+60+-+150+\" = \"+3x+%2B+27z+=+-90+\"
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\n" ); document.write( "\"+3x+%2B+27z+=+-90+\" is the second answer, once again let us put our two answers side by side
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\n" ); document.write( "First, \"++3x+%2B+8z+=+-14+\"
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\n" ); document.write( "Second, \"+3x+%2B+27z+=+-90+\", we can reduce this equation by dividing each side by \"3\", \"+3x+%2B+27z+=+-90+\" = \"+%283x+%2B+27z%29%2F3+=+-90%2F3+\" = \"+%283x%2F3%29+%2B+%2827z%2F3%29+=+-30+\" = \"+x+%2B+9z+=+-30+\"
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\n" ); document.write( "Our new equations are
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\n" ); document.write( "First, \"++3x+%2B+8z+=+-14+\"
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\n" ); document.write( "Second, \"+x+%2B+9z+=+-30+\"
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\n" ); document.write( "Now we need to solve for a variable again, doesn't matter which one, we will solve for \"x\"
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\n" ); document.write( "First, \"++3x+%2B+8z+=+-14+\", we need to move \"8z\" to the right side,
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\n" ); document.write( "\"++3x+%2B+8z+=+-14+\" = \"++3x+%2B+8z+-+8z+=++-14-8z+\" = \"++3x+=++-14-8z+\"
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\n" ); document.write( "Rearranging the right side, \"++3x+=++-14-8z+\" = \"++3x+=++-8z-14+\", we can solve for \"x\" by dividing each side by \"3\"
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\n" ); document.write( "\"++3x+=++-8z-14+\" = \"++3x%2F3+=++%28-8z-14%29%2F3+\" = \"++x+=++%28-8z-14%29%2F3+\"
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\n" ); document.write( "\"++%28-8z-14%29%2F3+\" is our first answer
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\n" ); document.write( "We can now solve for \"x\" in the second equation, \"+x+%2B+9z+=+-30+\"
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\n" ); document.write( "\"+x+%2B+9z+=+-30+\", we will move \"9z\" to the right side
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\n" ); document.write( "\"+x+%2B+9z+=+-30+\" = \"+x+%2B+9z-9z+=+-30-9z+\" = \"+x+=+-30-9z+\", rearranging the right side, \"+x+=+-30-9z+\" = \"+x+=+-9z-30\"
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\n" ); document.write( "\"+-9z-30\" is our second answer, let us put our two answers together
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\n" ); document.write( "First, \"++%28-8z-14%29%2F3+\"
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\n" ); document.write( "Second, \"+-9z-30\"
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\n" ); document.write( "Since our two answers equal \"x\" they will equal each other
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\n" ); document.write( " \"++%28-8z-14%29%2F3+=+-9z-30+\" = \"++%28-8z-14%29%2F3+=+%28-9z-30%29%2F1+\", using cross-multiplication
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\n" ); document.write( "\"++highlight%28-8z-14%29%2F3+=+%28-9z-30%29%2Fhighlight%281%29+\" = \"++%28-8z-14%29%2Fhighlight%283%29+=+highlight%28-9z-30%29%2F1+\"
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\n" ); document.write( "\"+%28-8z-14%29%281%29+=+%283%29%28-9z-30%29+\", rearranging the left side
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\n" ); document.write( "\"+%28-8z-14%29%281%29+=+%283%29%28-9z-30%29+\" = \"+%281%29%28-8z-14%29+=+%283%29%28-9z-30%29+\", using distribution
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\n" ); document.write( "\"+highlight%281%29%28highlight%28-8z%29-14%29+=+highlight%283%29%28highlight%28-9z%29-30%29+\" = \"+highlight%281%29%28-8z-highlight%2814%29%29+=+highlight%283%29%28-9z-highlight%2830%29%29+\"
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\n" ); document.write( "Remember the signs, \"+-8z+-+14+=+-27z+-+90+\", we will now solve for \"z\", we will move (-27z) to the left side
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\n" ); document.write( "\"+-8z+-+14+=+-27z+-+90+\" = \"+-8z%2B27z+-+14+=+-27z%2B+27z+-+90+\" = \"+19z+-+14+=++-+90+\", now we will move (-14) to the right side
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\n" ); document.write( "\"+19z+-+14+=++-+90+\" = \"+19z+-+14%2B14+=++-+90%2B14+\" = \"+19z+=++-+76+\", to solve \"z\" we will divide each side by \"19\"
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\n" ); document.write( "\"+19z+=++-+76+\" = \"+19z%2F19+=++-+76%2F19+\" = \"+z+=++-+4+\", to check our answer we will replace \"z\" with (-4) in our equation
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\n" ); document.write( "\"++%28-8z-14%29%2F3+=+-9z-30+\" = \"++%28-8%28-4%29-14%29%2F3+=+-9%28-4%29-30+\" = \"++%28%2832%29-14%29%2F3+=+%2836%29-30+\" = \"++%2818%29%2F3+=+%286%29+\" = \"++%286%29+=+%286%29+\" (True)
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\n" ); document.write( "Now that we know that \"+z+=+-4+\", we can replace it in one of the equations with two variables
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\n" ); document.write( "First, \"++3x+%2B+8z+=+-14+\"
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\n" ); document.write( "Second, \"+x+%2B+9z+=+-30+\"
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\n" ); document.write( "We will use the second equation, replace \"z\" with (-4)
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\n" ); document.write( "\"+x+%2B+9z+=+-30+\" = \"+x+%2B+9%28-4%29+=+-30+\" = \"+x+%2B+%28-36%29+=+-30+\" = \"+x++-36++=+-30+\", lets move (-36) to the right side
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\n" ); document.write( "\"+x++-36++=+-30+\" = \"+x++-36%2B36++=+-30%2B36+\" = \"+x++=+6+\"
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\n" ); document.write( "Let's check our answer by replacing \"x\" with \"6\", and \"z\" with (-4) in the equation,
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\n" ); document.write( "\"+x+%2B+9z+=+-30+\" = \"+%286%29+%2B+9%28-4%29+=+-30+\" = \"+6+%2B+%28-36%29+=+-30+\" = \"+6+-+36+=+-30+\" = \"+-30+=+-30+\" (True)
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\n" ); document.write( "\"x\" = \"6\"
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\n" ); document.write( "\"z\" = (-4),
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\n" ); document.write( "Now we can find \"y\" by replacing \"x\" and \"y\" in one of the three original equations
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\n" ); document.write( "x+2y=12
\n" ); document.write( "3y-4z=25
\n" ); document.write( "x+6y+z=20
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\n" ); document.write( "We will need to use the third equation, replace \"x\" with \"6\", \"z\" with (-4)
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\n" ); document.write( "\"+x%2B6y%2Bz=20+\" = \"+%286%29%2B6y%2B%28-4%29=20+\" = \"+%286%29%2B6y-+4=20+\" = \"+6-4%2B6y=20+\" = \"+2%2B6y=20+\", we will move \"2\" to the right side
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\n" ); document.write( "\"+2%2B6y=20+\" = \"+2-2%2B6y=20-2+\" = \"+6y=+18+\", to find \"y\", divide each side by \"6\"
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\n" ); document.write( "\"+6y=+18+\" = \"+6y%2F6=+18%2F6+\" = \"+y+=+3+\", we can check by replacing \"x\" with \"6\", \"y\" with \"3\", \"z\" with (-4) in the equation
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\n" ); document.write( "\"+x%2B6y%2Bz=20+\" = \"+%286%29%2B6%283%29%2B%28-4%29=20+\" = \"+6%2B18-4=20+\" = \"+24-4=20+\" = \"+20=20+\" ( True )
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\n" ); document.write( "x = 6
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\n" ); document.write( "y = 3
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\n" ); document.write( "z = (-4)
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\n" ); document.write( "We can check by replacing the other two original equations
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\n" ); document.write( "\"+x%2B2y=12+\" = \"+%286%29%2B2%283%29=12+\" = \"+6%2B6=12+\" = \"+12+=+12+\" (True)
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\n" ); document.write( "\"+3y-4z=25+\" = \"+3%283%29-4%28-4%29=25+\" = \"+9%2B+16=25+\" = \"+25+=+25+\" (True)
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\n" ); document.write( "x = 6
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\n" ); document.write( "y = 3
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\n" ); document.write( "z = (-4)
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\n" ); document.write( "ordered pairs are given as (x,y,z), our ordered pair = ( 6,3,-4)
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\n" ); document.write( "Hope I helped, Levi
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