1.25 . 7/19 + 5/4 . 15/19 - 5/4 : 19/3 = B
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18 tháng 3 2017
\(\dfrac{7}{-25}+\dfrac{18}{25}+\dfrac{4}{23}+\dfrac{5}{7}+\dfrac{19}{23}\)
=\(\left(\dfrac{-7}{25}+\dfrac{18}{25}\right)+\left(\dfrac{4}{23}+\dfrac{19}{23}\right)+\dfrac{5}{7}\)
= \(\dfrac{11}{25} +1+\dfrac{5}{7}\)
= \(1\dfrac{11}{25}+\dfrac{5}{7}\)
= \(2\dfrac{27}{175}\)
b) \(-2+\dfrac{15}{19}+\dfrac{-15}{17}+\dfrac{15}{23}+\dfrac{4}{19}\)
=\(-2+\left(\dfrac{ }{ }\right)\)
14 tháng 4 2022
a: \(\dfrac{3}{5}-\dfrac{7}{4}=\dfrac{12}{20}-\dfrac{35}{20}=\dfrac{-23}{20}\)
b: \(\dfrac{4}{5}:\dfrac{-8}{15}=\dfrac{-4}{5}\cdot\dfrac{15}{8}=\dfrac{-60}{40}=\dfrac{-3}{2}\)
c: \(=7+\dfrac{5}{9}-2-\dfrac{3}{4}-3-\dfrac{5}{9}=2-\dfrac{3}{4}=\dfrac{5}{4}\)
d: \(=\dfrac{-3}{7}\left(\dfrac{4}{19}+\dfrac{15}{19}\right)+\dfrac{5}{7}=\dfrac{2}{7}\)
3 tháng 4 2020
1) Ta có: \(\frac{-4}{7}-\frac{11}{19}+\frac{13}{19}\cdot\frac{-3}{7}+\frac{2}{19}:\frac{-7}{4}\)
\(=\frac{-4}{7}-\frac{11}{19}-\frac{39}{133}-\frac{8}{133}\)
\(=\frac{-76}{133}-\frac{77}{133}-\frac{39}{133}-\frac{8}{133}\)
\(=\frac{-200}{133}\)
2) Ta có: \(\left(\frac{-4}{9}+\frac{3}{5}\right):\frac{1}{\frac{1}{5}}+\left(\frac{1}{5}-\frac{5}{9}\right):\frac{1}{\frac{1}{5}}\)
\(=\left(\frac{-4}{9}+\frac{3}{5}\right)\cdot\frac{1}{5}+\left(\frac{1}{5}-\frac{5}{9}\right)\cdot\frac{1}{5}\)
\(=\frac{1}{5}\left(\frac{-4}{9}+\frac{3}{5}+\frac{1}{5}-\frac{5}{9}\right)\)
\(=\frac{1}{5}\left(-1+\frac{4}{5}\right)\)
\(=\frac{1}{5}\cdot\frac{-1}{5}=\frac{-1}{25}\)
3) Ta có: \(\frac{4}{5}-\left(-\frac{2}{7}\right)-\frac{7}{10}\)
\(=\frac{4}{5}+\frac{2}{7}-\frac{7}{10}\)
\(=\frac{56}{70}+\frac{20}{70}-\frac{49}{70}\)
\(=\frac{27}{70}\)
4) Ta có: \(\frac{2}{7}-\left(-\frac{13}{15}+\frac{4}{9}\right)-\left(\frac{5}{9}-\frac{2}{15}\right)\)
\(=\frac{2}{7}+\frac{13}{15}-\frac{4}{9}-\frac{5}{9}+\frac{2}{15}\)
\(=\frac{2}{7}+1-1=\frac{2}{7}\)
H9
HT.Phong (9A5)
CTVHS
27 tháng 7 2023
\(\dfrac{4}{19}\cdot-\dfrac{3}{7}+-\dfrac{3}{7}\cdot\dfrac{15}{19}+\dfrac{5}{7}\)
\(=-\dfrac{3}{7}\cdot\left(\dfrac{4}{19}+\dfrac{15}{19}\right)+\dfrac{5}{7}\)
\(=-\dfrac{3}{7}\cdot\dfrac{19}{19}+\dfrac{5}{7}\)
\(=-\dfrac{3}{7}+\dfrac{5}{7}\)
\(=\dfrac{-3+5}{7}\)
\(=\dfrac{2}{7}\)
DN
1
28 tháng 7 2023
` 4/19 . (-3)/7 + (-3)/7 . 15/19 + 5/7`
`= (-3)/7. ( 4/19 + 15/19 ) + 5/7`
`= (-3)/7 . 19/19 + 5/7`
`= (-3)/7 . 1 + 5/7`
`= (-3)/7 + 5/7`
`= 2/7`
1.25 . 7/19 + 5/4 . 15/19 - 5/4 : 19/3 =\(\frac{5}{4}\cdot\frac{7}{19}+\frac{5}{4}\cdot\frac{15}{19}-\frac{5}{4}\cdot\frac{3}{19}\)
\(\frac{5}{4}\left(\frac{7}{19}+\frac{15}{19}-\frac{3}{19}\right)=\frac{5}{4}=B\)