• # question_answer ${{i}^{2}}+{{i}^{4}}+{{i}^{6}}+......$upto $(2n+1)$ terms = [EAMCET 1980; Kerala (Engg.) 2005] A) $i$ B) $-i$ C) 1 D) $-1$

Given expression is$-1+1-1+1+.....$upto $(2n+1)$ terms Obviously number of terms is odd, so expression has the value -1.