Processing math: 6%

Saturday, August 1, 2015

2015/075) find x^{63} + x^{44} + x^{37} + x^{31} + x^{26} + x^9 +6

what is the value of the above expression for (x + \dfrac{1}{x})^2 = 3

we have
x^2 + 2 + \dfrac{1}{x^2}= 3
or x^4 -x^2 + 1=0
or (x^4-x^2+1) (x^2+1)= 0 as x^2+1 is not zero
or x^6+1=0

so x^6= - 1 and x^{12} = 1

so   x^{63} + x^{44} + x^{37}+ x^{31} + x^{26} + x^9 +6
= x^3 + x^8 + x + x^7 + x^2 + x^9 + 6 taking mod 12 of exponent
= x^3(x^6+1) + x^2(x^6+1) + x ( 1 + x^6) + 6
= 6 
This I have picked from https://in.answers.yahoo.com/question/index?qid=20150801013839AAEmdz0

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