document.write( "Question 732876: factorise 100n^2 + 400n - 32,000 = 0 \n" ); document.write( "
Algebra.Com's Answer #448084 by Edwin McCravy(20055)\"\" \"About 
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document.write( "100nē + 400n - 32,000 = 0\r\n" );
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document.write( "Factorise 100\r\n" );
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document.write( "100(nē + 4n - 320) = 0\r\n" );
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document.write( "Write down all the ways to factorise 320, starting\r\n" );
document.write( "with 320·1 and since the last sign is - write the \r\n" );
document.write( "difference of the two factors to the side:\r\n" );
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document.write( "320·1    320-1 = 319\r\n" );
document.write( "160·2    160-2 = 158\r\n" );
document.write( " 80·4     80-4 =  76\r\n" );
document.write( " 64·5     64-5 =  59\r\n" );
document.write( " 40·8     40-8 =  32\r\n" );
document.write( " 32·10   32-10 =  22\r\n" );
document.write( " 20·16   20-16 =   4\r\n" );
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document.write( "We find the coefficient of the middle term, which is 4,\r\n" );
document.write( "in the list of differences, so we use 20 and 16:\r\n" );
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document.write( "100(n + 20)(n - 16) = 0\r\n" );
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document.write( "To solve that we use the zero-factor principle:\r\n" );
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document.write( "100 = 0; n + 20 =   0;   n - 16 =  0 \r\n" );
document.write( "              n = -20;        n = 16\r\n" );
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document.write( "Edwin
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