\(\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+...+\frac{2}{99.101}\)
\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{2}{99}-\frac{2}{101}\)
\(=\frac{1}{3}-\frac{1}{101}=\frac{303}{303}-\frac{3}{303}=\frac{300}{303}\)
\(=\frac{100}{101}\)
\(\frac{2}{3.5}+\frac{2}{5.7}+\frac{2}{7.9}+...+\frac{2}{99.101}\)
\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+\frac{1}{7}-\frac{1}{9}+...+\frac{1}{99}-\frac{1}{101}\)
\(=\frac{1}{3}-\frac{1}{101}\)
\(=\frac{98}{303}\)
Vũ Cao Minh sai rồi kìa
Đáng nhẽ ra \(\frac{1}{3}\)= \(\frac{101}{303}\)chứ
2/3.5 + 2/5.7 + 2/7.9 + ... + 2/99.101
= 1/3 - 1/5 + 1/5 - 1/7 + 1/7 - 1/9 + ... + 1/99 - 1/101
= 1/3 - 1/101
= 98/303
