document.write( "Question 73947: How do you solve 3x2 - 5x = 8? \n" ); document.write( "
Algebra.Com's Answer #52961 by Edwin McCravy(20060)\"\" \"About 
You can put this solution on YOUR website!
how do you solve 3x2 - 5x = 8? \r\n" );
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document.write( "3x² - 5x = 8\r\n" );
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document.write( "This is a quadratic equation. \r\n" );
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document.write( "1. Get zero on the right by adding -8 to both sides\r\n" );
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document.write( "3x² - 5x - 8 = 0\r\n" );
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document.write( "2. Ignore the signs and multiply the 3 by the 8, getting 24\r\n" );
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document.write( "Think of two whole numbers whose product in 15 and whose\r\n" );
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document.write( "DIFFERENCE is 5. (DIFFERENCE because of the sign before the\r\n" );
document.write( " 8 is - . If it had been + I would have said \"SUM\")\r\n" );
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document.write( "A little thinking gives us 8 and 3, because\r\n" );
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document.write( "8×3 = 24 and 8-3 = 5\r\n" );
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document.write( "Rewrite the 5 as (8-3)\r\n" );
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document.write( "3x² - (8-3)x - 8 = 0\r\n" );
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document.write( "Remove the parentheses\r\n" );
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document.write( "3x² - 8x + 3x - 5 = 0\r\n" );
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document.write( "Factor x out of the first two terms\r\n" );
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document.write( "x(3x - 8) + 3x - 5 = 0\r\n" );
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document.write( "Factor 1 out of the last two terms:\r\n" );
document.write( "(Note: if you can't factor anything else \r\n" );
document.write( "out of one of the pair of terms, factor \r\n" );
document.write( "out 1 or -1.)\r\n" );
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document.write( "x(3x - 8) + 1(3x - 8) = 0\r\n" );
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document.write( "Now I'll do some coloring to help\r\n" );
document.write( "you see what I'm doing:\r\n" );
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document.write( "x(3x - 8) + 1(3x - 8) = 0\r\n" );
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document.write( "Now factor out the red (3x - 8),\r\n" );
document.write( "putting the blue x and the blue + 1 inside parentheses\r\n" );
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document.write( "(3x - 8)(x + 1) = 0\r\n" );
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document.write( "Set each factor = 0 and solve for x\r\n" );
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document.write( "3x - 8 = 0           x + 1 = 0\r\n" );
document.write( "    3x = 8               x = -1\r\n" );
document.write( "     x = 8/3\r\n" );
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document.write( "Edwin
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