5/5.10 + 5/10.15 + ... + 5/45.50
= 1/5 - 1/10 + 1/10 - 1/15 + ... + 1/45 - 1/50
= 1/5 - 1/50
= 9/50
\(\frac{5}{5\times10}+\frac{5}{10\times15}+...+\frac{5}{45\times50}\)
\(=\frac{1}{5}-\frac{1}{10}+\frac{1}{10}-\frac{1}{15}+...+\frac{1}{45}-\frac{1}{50}\)
\(=\frac{1}{5}-\frac{1}{50}\)
\(=\frac{9}{50}\)
~Study well~
#Thạc_Trân
\(\frac{5}{5\cdot10}+\frac{5}{10\cdot15}+...+\frac{5}{45\cdot50}\)
\(=\frac{1}{5}-\frac{1}{10}+\frac{1}{10}-\frac{1}{15}+...+\frac{1}{45}-\frac{1}{50}\)
\(=\frac{1}{5}-\frac{1}{50}=\frac{10-1}{50}=\frac{9}{50}\)
Đặt \(A=\frac{5}{5\cdot10}+\frac{5}{10\cdot15}+...+\frac{5}{45\cdot50}\)
\(A=\frac{1}{5}-\frac{1}{10}+\frac{1}{10}-\frac{1}{15}+...+\frac{1}{45}-\frac{1}{50}\)
\(A=\frac{1}{5}-\frac{1}{50}\)
\(=\frac{9}{50}\)
\(\frac{5}{5\cdot10}+\frac{5}{10\cdot15}+...+\frac{5}{45\cdot50}\)
\(=\frac{1}{5}-\frac{1}{10}+\frac{1}{10}-\frac{1}{15}+...+\frac{1}{45}-\frac{1}{50}\)
\(=\frac{1}{5}-\frac{1}{50}\)
\(=\frac{9}{50}\)
