Hãy nhập câu hỏi của bạn vào đây, nếu là tài khoản VIP, bạn sẽ được ưu tiên trả lời.
. Mik đang vội ( dấu " / " là phân số đó các bạn )
\(\dfrac{55}{11}\cdot6+\dfrac{55}{16}\cdot21+\dfrac{55}{21}\cdot26+\dfrac{55}{26}\cdot31+\dfrac{55}{31}\cdot36+\dfrac{55}{36}\cdot41=30+\dfrac{1155}{16}+\dfrac{1430}{21}+\dfrac{1705}{26}+\dfrac{1980}{31}+\dfrac{2255}{36}=\dfrac{12186720}{406224}+\dfrac{29324295}{406224}+\dfrac{27661920}{406224}+\dfrac{26638920}{406224}+\dfrac{25945920}{406224}+\dfrac{25445420}{406224}=\dfrac{147203195}{406224}\)
Đặt \(A=\frac{13}{3}+\frac{13}{6}+\frac{13}{10}+\frac{13}{15}+\frac{13}{21}+\frac{13}{28}+\frac{13}{36}+\frac{13}{45}+\frac{13}{55}\)
\(A=\frac{26}{6}+\frac{26}{12}+\frac{26}{20}+\frac{26}{30}+\frac{26}{42}+\frac{26}{56}+\frac{26}{72}+\frac{26}{90}+\frac{26}{110}\)
\(A=26\left(\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}+\frac{1}{110}\right)\)
\(A=26\left(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}+\frac{1}{10.11}\right)\)
\(A=26\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{10}-\frac{1}{11}\right)\)
\(A=26\left(\frac{1}{2}-\frac{1}{11}\right)\)
\(A=26.\frac{9}{22}\)
\(A=\frac{117}{11}\)
Vậy \(A=\frac{117}{11}\)
Chúc bạn học tốt ~
1: \(\dfrac{-7}{4}\cdot\dfrac{2}{9}=\dfrac{-14}{36}=\dfrac{-7}{18}\)
2: \(=\dfrac{12}{13}\cdot\dfrac{26}{5}=\dfrac{24}{5}\)
3: \(=\dfrac{20}{11}\cdot\dfrac{55}{21}=\dfrac{100}{21}\)
4: \(=\dfrac{-40}{240}=\dfrac{-1}{6}\)
a) \(S4=\frac{3}{50}+\frac{3}{150}+\frac{3}{300}+...+\frac{3}{9500}\)
\(S4=\frac{3}{5.10}+\frac{3}{10.15}+\frac{3}{15.20}+...+\frac{3}{95.100}\)
\(S4=\frac{3}{5}\left(\frac{1}{5}-\frac{1}{10}+\frac{1}{10}-\frac{1}{15}+\frac{1}{15}-\frac{1}{20}+...+\frac{1}{95}-\frac{1}{100}\right)\)
\(S4=\frac{3}{5}\left(\frac{1}{5}-\frac{1}{100}\right)\)
\(S4=\frac{3}{5}.\frac{19}{100}\)
\(S4=\frac{57}{500}\Rightarrow S=\frac{57}{500}:4=\frac{57}{2000}\)
b) \(S5=\frac{55}{11.16}+\frac{55}{16.21}+...+\frac{55}{36.41}\)
\(S5=\frac{55}{5}.\left(\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+...+\frac{1}{36}-\frac{1}{41}\right)\)
\(S5=11.\left(\frac{1}{11}-\frac{1}{41}\right)\)
\(S5=11.\frac{30}{451}\)
\(S5=\frac{30}{41}\Rightarrow S=\frac{30}{41}:5=\frac{6}{41}\)
Mình không hiểu ý bạn là S.4 hay là S4 là tên