tính nhanh:
\(\dfrac{-5}{7}\).\(\dfrac{2}{11}\)+\(\dfrac{-5}{7}\).\(\dfrac{9}{14}\)+1\(\dfrac{5}{7}\)
K
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18 tháng 7 2017
\(\dfrac{-5}{7}.\dfrac{2}{11}+\dfrac{-5}{7}.\dfrac{9}{14}+1\dfrac{5}{7}\)
\(=\dfrac{-5}{11}.\dfrac{2}{7}+\dfrac{-5}{11}.\dfrac{9}{7}+\dfrac{12}{7}\)
\(=\dfrac{-5}{11}\left(\dfrac{2}{7}+\dfrac{9}{7}\right)+\dfrac{12}{7}\)
\(=\dfrac{-5}{11}.\dfrac{11}{7}+\dfrac{12}{7}\)
\(=\dfrac{-5}{7}+\dfrac{12}{7}=\dfrac{7}{7}=1\)
PN
4
22 tháng 2 2022
\(=\dfrac{-5}{7}\left(\dfrac{2}{11}+\dfrac{9}{11}\right)+1+\dfrac{5}{7}=\dfrac{-5}{7}+\dfrac{5}{7}+1=1\)
SH
5 tháng 6 2021
Mik làm Bài 2 nhé ~
Bài 2 :
a) \(x-\dfrac{1}{2}=-\dfrac{1}{10}\)
\(x=-\dfrac{1}{10}+\dfrac{1}{2}\)
\(x=\dfrac{2}{5}\)
b) \(\dfrac{2}{3}x-\dfrac{7}{6}=\dfrac{5}{2}\)
\(\dfrac{2}{3}x=\dfrac{5}{2}+\dfrac{7}{6}\)
\(\dfrac{2}{3}x=\dfrac{11}{3}\)
\(x=\dfrac{11}{3}:\dfrac{2}{3}\)
\(x=\dfrac{11}{3}.\dfrac{3}{2}\)
\(x=\dfrac{11}{2}\)
c) \(2,5-\left(\dfrac{1}{8}x+\dfrac{1}{2}\right)=\dfrac{3}{4}\)
\(\left(\dfrac{1}{8}x+\dfrac{1}{2}\right)=2,5-\dfrac{3}{4}\)
\(\left(\dfrac{1}{8}x+\dfrac{1}{2}\right)=\dfrac{5}{2}-\dfrac{3}{4}\)
\(\dfrac{1}{8}x+\dfrac{1}{2}=\dfrac{7}{4}\)
\(\dfrac{1}{8}x=\dfrac{7}{4}-\dfrac{1}{2}\)
\(\dfrac{1}{8}x=\dfrac{5}{4}\)
\(x=10\)
5 tháng 6 2021
Bài 1:
a) \(\dfrac{-4}{11}.\dfrac{7}{9}+\dfrac{-4}{11}.\dfrac{2}{9}-\dfrac{7}{11}\)
\(=\dfrac{-4}{11}.\left(\dfrac{7}{9}+\dfrac{2}{9}\right)-\dfrac{7}{11}\)
\(=\dfrac{-4}{11}.1-\dfrac{7}{11}\)
\(=\dfrac{-4}{11}-\dfrac{7}{11}\)
\(=-1\)
b) \(\dfrac{3}{5}:\dfrac{-7}{10}+0,5-\left(\dfrac{-9}{14}\right)\)
\(=\dfrac{-6}{7}+\dfrac{1}{2}+\dfrac{9}{14}\)
\(=\dfrac{2}{7}\)
c) \(\dfrac{3}{5}-\dfrac{8}{5}:\left(5,25+75\%\right)\)
\(=\dfrac{3}{5}-\dfrac{8}{5}:\left(\dfrac{21}{4}+\dfrac{3}{4}\right)\)
\(=\dfrac{3}{5}-\dfrac{8}{5}:6\)
\(=\dfrac{3}{5}-\dfrac{4}{15}\)
\(=\dfrac{1}{3}\)
8 tháng 4 2022
b: =12+5/14-3-5/7-5-5/14
=4-5/7
=28/7-5/7=23/7
c: =(-2/5-11/10)+(7/11-7/11)
=-4/10-11/10=-15/10=-3/2
K
8 tháng 4 2022
\(a,\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{8}{13}-\dfrac{5}{13}\cdot\dfrac{2}{9}\)
\(=\dfrac{5}{9}\cdot\dfrac{7}{13}+\dfrac{5}{9}\cdot\dfrac{8}{13}-\dfrac{2}{13}\cdot\dfrac{5}{9}\)
\(=\dfrac{5}{9}\cdot\left(\dfrac{7}{13}+\dfrac{8}{13}-\dfrac{2}{13}\right)\)
\(=\dfrac{5}{9}\cdot\dfrac{14}{13}\)
\(=\dfrac{70}{117}\)
\(d,\dfrac{1}{2}+\dfrac{-2}{3}+\dfrac{1}{6}+\dfrac{-2}{5}\)
\(=\left(\dfrac{1}{2}+\dfrac{-2}{3}+\dfrac{1}{6}\right)+\dfrac{-2}{5}\)
\(=0+\dfrac{-2}{5}\)
\(=\dfrac{-2}{5}\)
HM
18 tháng 5 2017
B=(\(\dfrac{1}{5}\)-\(\dfrac{1}{5}\))+(\(\dfrac{3}{7}\)-\(\dfrac{3}{7}\))+(\(\dfrac{5}{9}\)-\(\dfrac{5}{9}\))+(\(\dfrac{2}{11}\)-\(\dfrac{2}{11}\))+(\(\dfrac{7}{13}\)-\(\dfrac{7}{13}\))+\(\dfrac{9}{16}\)
B=\(\dfrac{9}{16}\)
PN
18 tháng 7 2017
a) \(6\dfrac{5}{7}-\left(1\dfrac{3}{4}+2\dfrac{5}{7}\right)\)
\(=6\dfrac{5}{7}-1\dfrac{3}{4}-2\dfrac{5}{7}\)
\(=\left(6\dfrac{5}{7}-2\dfrac{5}{7}\right)-1\dfrac{3}{4}\)
\(=4-1\dfrac{3}{4}\)
\(=3\dfrac{3}{4}\)
PN
18 tháng 7 2017
b) \(7\dfrac{5}{11}-\left(2\dfrac{3}{7}+3\dfrac{5}{11}\right)\)
\(=7\dfrac{5}{11}-2\dfrac{3}{7}-3\dfrac{5}{11}\)
\(=\left(7\dfrac{5}{11}-3\dfrac{5}{11}\right)-2\dfrac{3}{7}\)
\(=4-2\dfrac{3}{7}\)
\(=2\dfrac{3}{7}\)
`-5/7 . 2/11 + (-5)/7 . 9/11 + 1 5/7`
`= -5/7 . (2/11 + 9/11) + 1 5/7`
`= -5/7 . 1 + 1 + 5/7`
`= -5/7 + 5/7 + 1`
`=1`.
\(=\dfrac{-5}{11}.\dfrac{2}{7}+\dfrac{-5}{11}.\dfrac{9}{7}+\dfrac{12}{7}\)
\(=-\dfrac{5}{11}\left(\dfrac{2}{7}+\dfrac{9}{7}\right)+\dfrac{12}{7}=-\dfrac{5}{11}.\dfrac{11}{7}+\dfrac{12}{7}\)
\(=\dfrac{-5}{7}+\dfrac{12}{7}=\dfrac{7}{7}=1\)