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Question:
if alpha and beta are the roots of the equation x2-x 1=0 then alpha power 2009 beta power 2009
Answer:

Given, x2 - x + 1 = 0

Now, by Shridharacharya formula, we het

      x = {1 ± √(1 - 4*1*1) }/2

=> x = {1 ± √(1 - 4) }/2

=> x = {1 ± √(-3)}/2

=> x = {1 ± √(3 * -1)}/2

=> x = {1 ± √3 * √-1}/2

=> x = {1 ± i√3}/2                            {since i = √-1}

=> x = {1 + i√3}/2, {--1 - i√3}/2

=> x = -{-1 - i√3}/2, -{-1 + i√3}/2

=> x = w, w2                                         {since w =  {-1 + i√3}/2 and w2 = {-1 - i√3}/2 }

Hence, α = -w, β = w2

Again we know that w3 = 1 and 1 + w + w2 = 0

Now, α2009 + β2009 = α2007 * α2 + β2007 * β2

                                = (-w)2007 * (-w)2 + (-w2 )2007 * (-w2 )2            {since 2007 is multiple of 3}

                                = -(w)2007 * (w)2 - (w2 )2007 * (w4 )

                                = -1 * w2 - 1 * w3 * w

                                = -1 * w2 - 1 * 1 * w

                                = -w2 - w

                                = 1                                  {since 1 + w + w2 = 0}

So, α2009 + β2009 = 1

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