document.write( "Question 76062: -9x+12y=18\r
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Algebra.Com's Answer #54605 by rmromero(383) $\"\"$ $\"About$

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document.write( "      -9x+12y=18\r
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document.write( "        x-2y=3\r
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document.write( "Here are the Steps using Substition method
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document.write( "1. In either equation, solve for one variable in terms of the other.\r
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document.write( "   x - 2y = 3
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document.write( "        x = 2y + 3 
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document.write( "2. Substitute for that variable in the other equation. Solve.\r
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document.write( "       -9x + 12y = 18,  x = 2y + 3 
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document.write( "      -9(2y + 3) + 12y = 18
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document.write( "      -18y - 27 + 12y = 18
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document.write( "              -6y = 45
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document.write( "                y = -45/6
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document.write( "                  = -15/2
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document.write( "3. Substitute the result from step 2 in either equation. Solve for the other variable.\r
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document.write( "         x - 2y = 3  , y = -15/2\r
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document.write( "         x - 2(-15/2) = 3
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document.write( "            x - (-15) = 3
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document.write( "               x + 15 = 3
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document.write( "                    x = -12\r
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document.write( "4. Check the solution in both original equations.
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document.write( "     
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document.write( "         x - 2y = 3, x = -12 and y = -15/2
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document.write( "  
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document.write( "         -12 - 2(-15/2) = 3
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document.write( "               -12 + 15 = 3
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document.write( "                      3 = 3  ------> true\r
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document.write( "                  -9x + 12y = 18, x = -12 and y = -15/2
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document.write( "        -9(-12) + 12(-15/2) = 18
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document.write( "                 108  -  90 = 18
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document.write( "                         18 = 18  ----> True\r
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document.write( "Therefore, the solution is x = -12 and y = -15/2\r
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document.write( "Visit my website:
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document.write( "http://onlinemathtutorial.tripod.com
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document.write( "Thanks \n" );
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