1.

Find the sum (`i + i^(2) + i^(3) + i^(4) +.....` up to 400 terms).

Answer» Given sum `=(i+i^(2)+i^(3)+i^(4))+(i^(5)+i^(6)_i^(7)+i^(8))+.......`
`=(i+i^(2)+i^(3)+1)+i^(5)(1+i+i^(2)+i^(3))+....=0." "[because (1+i+i^(2)+i^(3))=0]`


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