Biết

Câu hỏi: Biết $1 +\hspace{0.17em}i + i^2 +\hspace{0.17em}....+ i^{100} = a+bi (a,b \in \mathrm{ℝ})$. Tìm a,b.

$A. \left\{\begin{array}{l}a = 0\\ b = 1\end{array}\right.$

$B. \left\{\begin{array}{l}a = 1\\ b = 0\end{array}\right.$

$C. \left\{\begin{array}{l}a = 1\\ b = 1\end{array}\right.$

$D. \left\{\begin{array}{l}a = -1\\ b = -1\end{array}\right.$