Classical Algebra (Math 326) Written Assignment

due Wednesday, April 25, 2001

Directions

There will be a premium placed on accuracy in the grading of this assignment. Please submit your assignment typed. If there is more than one page, please staple.
Explain your solutions.

The Analogy Between Z and F[x] when F is a field

  1. Greatest Common Divisor of Polynomials over a Finite Field

    Find the monic greatest common divisor over the finite field F_{5} of the two polynomials

     x^{4} - 1    and    x^{4} - 3 x^{2} + 1  .  

  2. Bezout's Identity for Polynomials

    The monic greatest common divisor of the polynomials

     f(x)  =  x^{5} - x + 1    and    g(x)  =  x^{3} - x + 1  , 

    regarded as polynomials with rational coefficients, is the constant polynomial 1. Express 1 as a polynomial linear combination of f and g. (Be sure to verify the correctness of your answer by expanding the linear combination.)

  3. (x-2)-adic Expansion of a Polynomial

    Expand the polynomial x^{5} - x + 1 relative to the base x - 2 in the ring of polynomials with rational coefficients.

  4. Solving a Polynomial Congruence

    Determine all polynomials f(x) with rational coefficients for which the polynomial congruence

     (x^{3} + 2 x^{2} - x - 2) . f(x) EQUIV x^{2} + 2 x - 3   mod x^{2} - 3 x + 2 

    is satisfied.

  5. (x-1)-adic Expansion of a Polynomial Fraction

    Recall that rational numbers, i.e., integer ratios, have decimal expansions relative to a given base. Find the analogous expansion for the ratio of polynomials (with rational coefficients)

     {x}/{x^{2} - 3 x + 3} 

    relative to (x - 1) as the polynomial base.

    Do the ``digits'' repeat for this example?


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