Câu trả lời:
A=196197+197198=(1−1197)+(1−1198)=1−1197+1−1198=1−1197+197197−1198A=196197+197198=(1−1197)+(1−1198)=1−1197+1−1198=1−1197+197197−1198\(=1-\frac{198}{197}-\frac{1}{198}=\frac{197}{197}-\frac{198}{197}-\frac{1}{198}=\frac{-1}{197}-\frac{1}{198}