Câu hỏi 11Tìm A trong $\dfrac A{1\times3}+\dfrac A{3\times5}+\dfrac A{5\times7}+\cdots+\dfrac A{97\times99}=1$?$\frac{98}{99}$$\frac{99}{196}$$\frac{99}{98}$$\frac{99}{49}$