Factorization of Polynomials over a field

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SUMMARY

The discussion focuses on the factorization of the polynomial x³ - 23x² - 97x + 291 over finite fields Z3[x], Z7[x], and Z11[x]. The polynomial is shown to be reducible over Z3, where it factors into X(X² + X + 2), but the quadratic X² + X + 2 has no roots in Z/3Z. In Z7, the polynomial is confirmed to be irreducible as it has no roots. Similarly, in Z11, the polynomial is also irreducible after testing potential roots, confirming that it does not factor over this field.

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  • Understanding of polynomial factorization
  • Familiarity with finite fields, specifically Z3, Z7, and Z11
  • Knowledge of root testing in modular arithmetic
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lilcoley23@ho
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I don't understand how to factor a polynomial over Z3 [x], Z7 [x], and Z11 [x]

I need to factor the polynomail x3 - 23x2 - 97x + 291

PLEASE HELP!
 
Last edited:
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Note that for a polynomial is of degree 2 and 3, reducibility is equivalent to the existence of roots.

mod 3:

X^3-23X^2-97X+291=X^3+X^2+2X=X(X^2+X+2). A calculation shows X^2+X+2 doesn't have a root in Z/3Z. Done.

mod 7:
X^3+5X^2+2X+4. A calculation shows it has no root in Z/7Z. The polynomial is irreducible.

mod 11:
291=5=1*5=10*6. So if the polynomial has a root, it should be 1, 5, 6, or 10. A calculation shows X^3-X^2+2X+5 has no root. The given poly is irreducible.
 
I think I might have phrased this question wrong, but I figured it out.

THANKS
 

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