\(\frac{5^2}{1.6}+\frac{5^2}{6.11}+...+\frac{5^2}{1001.1006}\)
\(=5\left(\frac{5}{1.6}+\frac{5}{6.11}+...+\frac{5}{1001.1006}\right)\)
\(=5\left(1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+...+\frac{1}{1001}-\frac{1}{1006}\right)\)
\(=5\left(1-\frac{1}{1006}\right)\)
\(=5.\frac{1005}{1006}\)
\(=\frac{5025}{1006}\)
\(\frac{5^2}{1.6}+\frac{5^2}{6.11}+...+\frac{5^2}{1001.1006}\)
\(=5.\left(\frac{5}{1.6}+\frac{5}{6.11}+\frac{5}{11.16}+...+\frac{5}{1001.1006}\right)\)
\(=5.\left(1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+\frac{1}{11}-\frac{1}{16}+...+\frac{1}{1001}-\frac{1}{1006}\right)\)
\(=5.\left(1-\frac{1}{1006}\right)\)
\(=\frac{5.1005}{1006}=\frac{5025}{1006}\)
Ủng hộ mk nha !!! ^_^