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Homework Help: Help with 2 problems!

  1. Mar 22, 2010 #1
    1. The problem statement, all variables and given/known data

    1) Find the General Solution to:
    (D3 - D2 + D - I)[y] = t5 + 1

    2) Prove or disprove that there are two constants A and B such that:
    t2D - tD - 8I = (tD + AI)(tD + BI)

    2. Relevant equations

    3. The attempt at a solution

    1) I can't figure out how to attempt this one. Doesn't make sense to me.
    2) I should FOIL out the RHS of the equation, but I did that on paper and it didn't make too much sense to me.
  2. jcsd
  3. Mar 22, 2010 #2


    User Avatar
    Homework Helper
    Gold Member

    There are two methods that immediately come to mind:

    (1)Use the method of Undetermined Coefficients

    (2)Use the annihilator method

    Show us what you've got, and keep in mind that to calculate something like [itex]D(tD)[/itex] you need to use the product rule.
  4. Mar 23, 2010 #3
    There was a typo in #2:

    2) Prove or disprove that there are two constants A and B such that:
    t2D2 - tD - 8I = (tD + AI)(tD + BI)
  5. Mar 24, 2010 #4


    Staff: Mentor

    There are solutions for A and B if you permit complex solutions.
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