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An equation with degree 3

  1. Oct 28, 2011 #1
    I have an equation similar:
    8x^3+4cx^2+2(b-3)x+(a-2c)=0
    a, b, c are real number.
    if p, q , t be roots.
    What can say about (p+q-2t) and (p^2+ q^2-2t^2)???
    Please help me??
    Thanks so much.
     
  2. jcsd
  3. Oct 28, 2011 #2

    Deveno

    User Avatar
    Science Advisor

    hint: write your polynomial as 8(x-p)(x-q)(x-t) and multiply it out, then compare coefficients.
     
  4. Oct 28, 2011 #3
    I know
    p+q+t=c/2
    pq+pt+qt=(b-3)/4
    pqt=(2c-a)/8
    but I need value for
    (p+q-2t)??
    (p^2+ q^2-2t^2)???
    Please help me??
     
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