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DP
1
S
1
5 tháng 11 2021
\(=\dfrac{11}{17}:\dfrac{19}{40}+\dfrac{11}{17}:\dfrac{23}{20}=\dfrac{11}{17}\cdot\left(\dfrac{40}{19}+\dfrac{20}{23}\right)=\dfrac{11}{17}\cdot\dfrac{1300}{437}=\dfrac{14300}{7429}\)
16 tháng 8 2021
Ta có: \(D=\left(2\dfrac{2}{15}\cdot\dfrac{9}{17}\cdot\dfrac{3}{32}\right):\left(-\dfrac{3}{17}\right)\)
\(=\dfrac{32}{15}\cdot\dfrac{9}{17}\cdot\dfrac{3}{32}\cdot\dfrac{-17}{3}\)
\(=\dfrac{-9}{15}=-\dfrac{3}{5}\)
BN
1
11 tháng 8 2020
11/125 - 17/18 - 5/7 + 4/9 + 17/14
=11/125 - (17/18 - 4/9) - (5/7 -17/14)
=11/125 - (17/18 - 8/18) - (10/14 - 17/14)
=11/125 - 9/18 + 7/14
=11/125 - 1/2 + 1/2
=11/125 (= 0,88)
NT
1
25 tháng 6 2021
Ta có: \(\dfrac{8}{9}-\dfrac{1}{72}-\dfrac{1}{56}-\dfrac{1}{42}-\dfrac{1}{30}-\dfrac{1}{20}-\dfrac{1}{12}-\dfrac{1}{6}-\dfrac{1}{2}\)
\(=\dfrac{8}{9}-\left(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{30}+\dfrac{1}{42}+\dfrac{1}{56}+\dfrac{1}{72}\right)\)
\(=\dfrac{8}{9}-\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{9}\right)\)
\(=\dfrac{8}{9}-\left(1-\dfrac{1}{9}\right)\)
\(=\dfrac{8}{9}-\dfrac{8}{9}=0\)
DL
19 tháng 11 2018
\(\frac{-3}{11}:\frac{17}{15}+\frac{-3}{11}:\frac{17}{2}+\frac{8}{11}\)
\(=\frac{-3}{11}.\frac{15}{17}+\frac{-3}{11}.\frac{2}{17}+\frac{8}{11}\)
\(=\frac{-3}{11}.\left(\frac{15}{17}+\frac{2}{17}\right)+\frac{8}{11}\)
\(=\frac{-3}{11}.1+\frac{8}{11}\)
\(=\frac{-3}{11}+\frac{8}{11}\Rightarrow\frac{5}{11}\)
K mik nhe
19 tháng 11 2018
\(\frac{-3}{11}:\frac{17}{15}+\frac{-3}{11}:\frac{17}{2}+\frac{8}{11}\)
\(=\frac{-3}{11}.\left(\frac{15}{17}+\frac{2}{17}\right)+\frac{8}{11}\)
\(=\frac{-3}{11}.1+\frac{8}{11}\)
=\(\frac{-3}{11}+\frac{8}{11}\)
\(=\frac{5}{11}\)
MX
2
9 tháng 2 2021
Ta đặt A=\(-\left(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+\dfrac{1}{30}+\dfrac{1}{42}+\dfrac{1}{56}+\dfrac{1}{72}+\dfrac{1}{90}\right)\)
\(\Rightarrow A=-\left(\dfrac{1}{1\cdot2}+\dfrac{1}{2\cdot3}+\dfrac{1}{3\cdot4}+\dfrac{1}{4\cdot5}+\dfrac{1}{5\cdot6}+\dfrac{1}{6\cdot7}+\dfrac{1}{7\cdot8}+\dfrac{1}{8\cdot9}+\dfrac{1}{9\cdot10}\right)\)= \(-\left(1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{8}-\dfrac{1}{9}+\dfrac{1}{9}-\dfrac{1}{10}\right)\)
= - \(\left(1-\dfrac{1}{10}\right)=-\left(\dfrac{10-1}{10}\right)=-\dfrac{9}{10}\)
9 tháng 2 2021
Ta có: \(-\dfrac{1}{90}-\dfrac{1}{72}-\dfrac{1}{56}-\dfrac{1}{42}-\dfrac{1}{30}-\dfrac{1}{20}-\dfrac{1}{12}-\dfrac{1}{6}-\dfrac{1}{2}\)
\(=-\left(\dfrac{1}{90}+\dfrac{1}{72}+\dfrac{1}{56}+\dfrac{1}{42}+\dfrac{1}{30}+\dfrac{1}{20}+\dfrac{1}{12}+\dfrac{1}{6}+\dfrac{1}{2}\right)\)
\(=-\left(\dfrac{1}{9}-\dfrac{1}{10}+\dfrac{1}{8}-\dfrac{1}{9}+\dfrac{1}{7}-\dfrac{1}{8}+\dfrac{1}{6}-\dfrac{1}{7}+\dfrac{1}{5}-\dfrac{1}{6}+\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{2}\right)\)
\(=-\left(-\dfrac{1}{10}+1\right)\)
\(=-\left(1-\dfrac{1}{10}\right)\)
\(=-\left(\dfrac{10}{10}-\dfrac{1}{10}\right)=-\dfrac{9}{10}\)
= - 69 bn nha
tk cho mk đi
(42-69+17)-(42+17)
=44-69+17+42+17
=(42-42)-(17-17)-69
=0-0-69
=-69
ai k mình mình k lại