1: \(M=\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{49}-\dfrac{1}{50}=\dfrac{1}{2}-\dfrac{1}{50}=\dfrac{24}{50}=\dfrac{12}{25}\)
2: \(N=8\left(\dfrac{1}{10}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{12}+...+\dfrac{1}{69}-\dfrac{1}{70}\right)\)
\(=8\left(\dfrac{1}{10}-\dfrac{1}{70}\right)\)
\(=8\cdot\dfrac{6}{70}=\dfrac{48}{70}=\dfrac{24}{35}\)
3: \(P=\dfrac{1}{2}\left(1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+...+\dfrac{1}{47}-\dfrac{1}{49}\right)=\dfrac{1}{2}\cdot\dfrac{48}{49}=\dfrac{24}{49}\)
4: \(Q=1-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{11}=1-\dfrac{1}{11}=\dfrac{10}{11}\)
giúp mik với, mik đang cần gấp, các bạn làm nhanh giúp mik nhé, bạn nào nhanh nhất mik tặng tim
