Tính:
D=\(\frac{6}{3.5}+\frac{6}{5.7}+...+\frac{6}{21.23}\)
E=\(\frac{20}{11.13}+\frac{20}{13.15}+\frac{20}{15.17}+...+\frac{20}{53.55}\)
G=\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+...+\frac{1}{9900}\)
LÀM HỘ MÌNH VỚI MAI THI RỒI HUHU ..T.T
Cầu thánh toán nào lướt qua hay ai biết làm thì giải hộ mình nhé chi tiết càng tốt hứa tick trả đầy đủ
Bài làm
\(D=\frac{6}{3,5}+\frac{6}{5.7}+...+\frac{6}{21.23}\)
\(D=3.\left(\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{21.23}\right)\)
\(D=3.\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{21}-\frac{1}{23}\right)\)
\(D=3.\left(\frac{1}{3}-\frac{1}{23}\right)\)
\(D=3.\frac{20}{69}\)
\(D=\frac{20}{23}\)
Học tốt
Bài làm
\(D=\frac{6}{3.5}+\frac{6}{5.7}+...+\frac{6}{21.23}\)
\(D=3.\left(\frac{2}{3.5}+\frac{2}{5.7}+...+\frac{2}{21.23}\right)\)
\(D=3.\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{21}-\frac{1}{23}\right)\)
\(D=3.\left(\frac{1}{3}-\frac{1}{23}\right)\)
\(D=3.\frac{20}{69}\)
\(D=\frac{20}{23}\)
\(E=\frac{20}{11.13}+\frac{20}{13.15}+\frac{20}{15.17}+...+\frac{20}{53.55}\)
\(E=10.\left(\frac{2}{11.13}+\frac{2}{13.15}+\frac{2}{15.17}+...+\frac{2}{53.55}\right)\)
\(E=10.\left(\frac{1}{11}-\frac{1}{13}+\frac{1}{13}-\frac{1}{15}+\frac{1}{15}-\frac{1}{17}+...+\frac{1}{53}-\frac{1}{55}\right)\)
\(E=10.\left(\frac{1}{11}-\frac{1}{55}\right)\)
\(E=10.\frac{4}{55}\)
\(E=\frac{8}{11}\)
\(G=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+...+\frac{1}{9900}\)
\(G=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+...+\frac{1}{99.100}\)
\(G=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+...+\frac{1}{99}-\frac{1}{100}\)
\(G=\frac{1}{1}-\frac{1}{100}\)
\(G=\frac{99}{100}\)
Nhớ k cho m nha
Ta có:
\(D=\frac{6}{3\cdot5}+\frac{6}{5\cdot7}+...+\frac{6}{21\cdot23}\)
\(D=3.\left(\frac{2}{3.5}+\frac{2}{5\cdot7}+...+\frac{2}{21.23}\right)\)
\(D=3.\left(\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{21}-\frac{1}{23}\right)\)
\(D=3.\left(\frac{1}{3}-\frac{1}{23}\right)\)
\(D=3.\frac{20}{69}\)
\(D=\frac{20}{23}\)
Vậy \(D=\frac{20}{23}\)
D=\(\frac{6}{3.5}\)+\(\frac{6}{5.7}\)+...........+\(\frac{6}{21.23}\)
\(\frac{1}{3}\)D=\(\frac{1}{3}\).(\(\frac{6}{3.5}\)+\(\frac{6}{5.7}\)+...............+\(\frac{6}{21.23}\))
\(\frac{1}{3}\)D=\(\frac{1}{3}\).\(\frac{6}{3.5}\)+\(\frac{1}{3}\).\(\frac{6}{5.7}\)+................+\(\frac{1}{3}\).\(\frac{6}{21.23}\)
\(\frac{1}{3}\)D=\(\frac{2}{3.5}\)+\(\frac{2}{5.7}\)+.............................+\(\frac{2}{21.23}\)
\(\frac{1}{3}\)D=\(\frac{1}{3}\)-\(\frac{1}{5}\)+\(\frac{1}{5}\)-\(\frac{1}{7}\)+..................+\(\frac{1}{21}\)-\(\frac{1}{23}\)
\(\frac{1}{3}\)D=\(\frac{1}{3}\)-\(\frac{1}{23}\)
\(\frac{1}{3}\)D=\(\frac{20}{69}\)
D=\(\frac{20}{69}\):\(\frac{1}{3}\)
D=\(\frac{20}{69}\).3
D=\(\frac{20}{23}\)
E=\(\frac{20}{11.13}\)+\(\frac{20}{13.15}\)+\(\frac{20}{15.17}\)+...............+\(\frac{20}{53.55}\)
\(\frac{1}{10}\)E=\(\frac{1}{10}\).(\(\frac{20}{11.13}\)+\(\frac{20}{13.15}\)+\(\frac{20}{15.17}\)+................+\(\frac{20}{53.55}\))
\(\frac{1}{10}\)E=\(\frac{1}{10}\).\(\frac{20}{11.13}\)+\(\frac{1}{10}\).\(\frac{20}{13.15}\)+\(\frac{1}{10}\).\(\frac{20}{15.17}\)+..............+\(\frac{1}{10}\).\(\frac{20}{53.55}\)
\(\frac{1}{10}\)E=\(\frac{2}{11.13}\)+\(\frac{2}{13.15}\)+\(\frac{2}{15.17}\)+...................+\(\frac{2}{53.55}\)
\(\frac{1}{10}\)E=\(\frac{1}{11}\)-\(\frac{1}{13}\)+\(\frac{1}{13}\)-\(\frac{1}{15}\)+\(\frac{1}{15}\)-\(\frac{1}{17}\)+.............+\(\frac{1}{53}\)-\(\frac{1}{55}\)
\(\frac{1}{10}\)E=\(\frac{1}{11}\)-\(\frac{1}{55}\)
\(\frac{1}{10}\)E=\(\frac{4}{55}\)
E=\(\frac{4}{55}\):\(\frac{1}{10}\)
E=\(\frac{4}{55}\).10
E=\(\frac{8}{11}\)
