- #1
ben9703
- 3
- 0
hi i have this homework question and I am not sure if my thought process is valid.
The Question:
let a, b and c be roots of the polynomial equation: x^3+px+q=0 and S(n)=(a^n)+(b^n)+(c^n)
now prove: that for S(n)= -p(S(n-2))-q(S(n-3)) for n>3my attempt:
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first off i just played around with the equation. S(1)=0 , S(2)=-2p , S(3)=-3q after this all following values can be found by rearranging the polynomial to... x^3=-px-q and multiplying through x for each successive value of n. from this its clear how the above function ( S(n)= -p(S(n-2))-q(S(n-3)) ) arises. what I am not sure about is the pure mathematical proof to proving this (n>3).
if anybody could shine some light on the question or just share ideas i would be very grateful. Thanks :)
The Question:
let a, b and c be roots of the polynomial equation: x^3+px+q=0 and S(n)=(a^n)+(b^n)+(c^n)
now prove: that for S(n)= -p(S(n-2))-q(S(n-3)) for n>3my attempt:
-------------
first off i just played around with the equation. S(1)=0 , S(2)=-2p , S(3)=-3q after this all following values can be found by rearranging the polynomial to... x^3=-px-q and multiplying through x for each successive value of n. from this its clear how the above function ( S(n)= -p(S(n-2))-q(S(n-3)) ) arises. what I am not sure about is the pure mathematical proof to proving this (n>3).
if anybody could shine some light on the question or just share ideas i would be very grateful. Thanks :)