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Topic: 3xCubed + 10xSquared - 3x = Integer (Read 457 times) |
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ThudnBlunder
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3xCubed + 10xSquared - 3x = Integer
« on: Jan 20th, 2009, 5:30pm » |
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For which (reduced) fractions x is 3x3 + 10x2 - 3x an integer?
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balakrishnan
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Re: 3xCubed + 10xSquared - 3x = Integer
« Reply #1 on: Jan 20th, 2009, 11:15pm » |
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| hidden: | 1)All integers n
2)The set of all fractions of the form x=(9n+ 8 )/3 where n is an integer and the corresponding 3*x^3+10*x^2-3*x is 81*n^3 + 306*n^2 + 343*n + 120 |
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