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Old 2019-08-04, 07:35   #10
Nick
 
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Dec 2012
The Netherlands

6DE16 Posts
Default Polynomials from right to left

Let f,g and h be polynomials with non-zero constant term.
Write F, G and H for the polynomials you get by reversing the coefficients.
For example, if f=2x³+5x²-3x+4 then F=4x³-3x²+5x+2 (obtained by reading f from right to left).
Then fg=h if and only if FG=H.
This is a useful little trick, for example, when you need to determine whether a polynomial is irreducible.
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