document.write( "Question 1144532: 15x^2+8x-12=0 \n" ); document.write( "

Algebra.Com's Answer #765678 by Edwin McCravy(20056) $\"\"$ $\"About$

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15x²+8x-12 = 0\r\n" );
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document.write( "Use the \"AC\" method:\r\n" );
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document.write( "Multiply 15 by 12, first and last numbers.\r\n" );
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document.write( "15×12 = 180\r\n" );
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document.write( "Look for two factors of 180 that differ by 8, the middle coefficient.\r\n" );
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document.write( "Doesn't take long to see that they are 18 and 10.\r\n" );
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document.write( "Give them signs necessary to form middle coefficient +8.\r\n" );
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document.write( "That is, +18-10 equals +8\r\n" );
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document.write( "So we write 15x²+8x-12 = 0 as\r\n" );
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document.write( "15x²+18x-10x-12 = 0\r\n" );
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document.write( "Factor the first two terms by taking out 3x\r\n" );
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document.write( "3x(5x+6)-10x-12 = 0\r\n" );
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document.write( "Factor the last two terms by taking out -2\r\n" );
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document.write( "3x(5x+6)-2(5x+6) = 0\r\n" );
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document.write( "Factor the whole left side by taking out (5x+6)\r\n" );
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document.write( "(5x+6)(3x-2) = 0\r\n" );
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document.write( "Set each factor = 0\r\n" );
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document.write( "5x+6=0;  3x-2=0\r\n" );
document.write( "  5x=-6;   3x=2\r\n" );
document.write( "   x=-6/5;  x=2/3\r\n" );
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document.write( "Edwin

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