Question

answer for this question

Answer 1

First, notice that 1+i=2–√(cosπ4+isinπ4) and 1−i=2–√(cos(−π4)+isin(−π4)).

Using de Moivre's formula and the fact that sin is odd and cos is even, we get

(1+i)n+(1−i)n=2(root 2)^n cos nπ/4

therefore n+2/2=3n/2

             n+2=3n

               n=1     (Ans)

Hope it helps!!!!!