document.write( "Question 604899: How do I solve systems of equations by substitution for example
\n" ); document.write( " $\"1%2F2\"$ x + $\"3%2F4\"$ y = $\"-7%2F4\"$
\n" ); document.write( " $\"5%2F6\"$ x - $\"1%2F6\"$ y = $\"4%2F3\"$ \n" ); document.write( "

Algebra.Com's Answer #381480 by AnlytcPhil(1806) $\"\"$ $\"About$

You can put this solution on YOUR website!

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document.write( "        x + y = \r\n" );
document.write( "        x - y = \r\n" );
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document.write( "Before you do anything else get rid of those fractions.  \r\n" );
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document.write( "Multiply the first equation through by the LCD of 4:\r\n" );
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document.write( "    4·x + 4·y = 4·\r\n" );
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document.write( "        2x + 3y = -7\r\n" );
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document.write( "Multiply the second equation through by the LCD of 6:\r\n" );
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document.write( "   6·x - 6·y = 6·\r\n" );
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document.write( "        5x -  y =  8\r\n" );
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document.write( "Now the system is \r\n" );
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document.write( "        2x + 3y = -7\r\n" );
document.write( "        5x -  y =  8\r\n" );
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document.write( "Solve the second equation for y\r\n" );
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document.write( "             -y = 8 - 5x\r\n" );
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document.write( "Divide through by -1\r\n" );
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document.write( "              y = -8 + 5x\r\n" );
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document.write( "Substitute -8 + 5x for y in the\r\n" );
document.write( "first equation:\r\n" );
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document.write( "        2x + 3y = -7\r\n" );
document.write( "2x + 3(-8 + 5x) = -7\r\n" );
document.write( "  2x - 24 + 15x = -7\r\n" );
document.write( "            17x = 17\r\n" );
document.write( "              x = 1\r\n" );
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document.write( "Substitute 1 for x in \r\n" );
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document.write( "              y = -8 + 5x\r\n" );
document.write( "              y = -8 + 5(1)\r\n" );
document.write( "              y = -8 + 5\r\n" );
document.write( "              y = -3\r\n" );
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document.write( "Solution: (x,y) = (1,-3)\r\n" );
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document.write( "Edwin

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