Tính.
a) \(\dfrac{5}{7}\times\dfrac{7}{15}\) b) \(\dfrac{8}{21}\times3\) c) \(\dfrac{24}{17}:\dfrac{9}{17}\) d) \(\dfrac{36}{5}:9\)
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GL
25 tháng 8 2023
a) \(\dfrac{3}{5}+\dfrac{7}{25}=\dfrac{15}{25}+\dfrac{7}{25}=\dfrac{15+7}{25}=\dfrac{22}{25}\)
b) \(\dfrac{8}{11}-\dfrac{19}{33}=\dfrac{24}{33}-\dfrac{19}{33}=\dfrac{24-19}{33}=\dfrac{5}{33}\)
c) \(\dfrac{16}{21}\times\dfrac{3}{5}=\dfrac{16\times3}{21\times5}=\dfrac{48}{105}=\dfrac{16}{35}\)
d) \(\dfrac{14}{41}\div\dfrac{7}{9}=\dfrac{14}{41}\times\dfrac{9}{7}=\dfrac{14\times9}{41\times7}=\dfrac{126}{287}=\dfrac{18}{41}\)
21 tháng 5 2022
a: \(=\left(\dfrac{17}{10}+\dfrac{70}{10}-\dfrac{87}{10}\right):\left(\dfrac{23}{4}-\dfrac{11}{4}+\dfrac{9}{25}\right)\cdot\left(12,98\cdot0,25\right)+12,5\)
\(=0:\left(3+\dfrac{9}{25}\right)\cdot\left(12,98+0,25\right)+12,5\)
=12,5
b: \(=\dfrac{13}{12}\cdot\dfrac{27}{5}\cdot2\cdot\dfrac{34}{9}\cdot2\cdot\dfrac{2}{17}\)
\(=\dfrac{13}{12}\cdot2\cdot\dfrac{27}{5}\cdot\dfrac{34}{9}\cdot\dfrac{4}{17}\)
\(=\dfrac{13}{6}\cdot\dfrac{27}{5}\cdot\dfrac{8}{9}=\dfrac{8}{6}\cdot3\cdot\dfrac{13}{5}=4\cdot\dfrac{13}{5}=\dfrac{52}{5}\)
VT
31 tháng 12 2022
\(C=\dfrac{4}{9}\times\dfrac{13}{17}+\dfrac{4}{17}\times\dfrac{4}{9}+\dfrac{2}{9}\\ =\dfrac{4}{9}\times\left(\dfrac{13}{17}+\dfrac{4}{17}\right)+\dfrac{2}{9}\\ =\dfrac{4}{9}\times1+\dfrac{2}{9}\\ =\dfrac{4}{9}+\dfrac{2}{9}\\ =\dfrac{6}{9}=\dfrac{2}{3}\)
\(D=\dfrac{8}{19}\times\dfrac{5}{11}+\dfrac{7}{11}\times\dfrac{8}{19}+\dfrac{12}{11}\times\dfrac{11}{19}\\ =\dfrac{8}{19}\times\left(\dfrac{5}{11}+\dfrac{7}{11}\right)+\dfrac{12}{11}\times\dfrac{11}{19}\\ =\dfrac{8}{19}\times\dfrac{12}{11}+\dfrac{12}{11}\times\dfrac{11}{19}\\ =\dfrac{12}{11}\times\left(\dfrac{8}{19}+\dfrac{11}{19}\right)\\ =\dfrac{12}{11}\times19\\ =\dfrac{12}{11}\)
31 tháng 12 2022
\(C=\dfrac{4}{9}\cdot\dfrac{13}{17}+\dfrac{4}{17}\cdot\dfrac{4}{9}+\dfrac{2}{9}\)
\(C=\dfrac{4}{9}\cdot\left(\dfrac{13}{17}+\dfrac{4}{17}\right)+\dfrac{2}{9}\)
\(C=\dfrac{4}{9}\cdot\dfrac{13+4}{17}+\dfrac{2}{9}\)
\(C=\dfrac{4}{9}\cdot\dfrac{17}{17}+\dfrac{9}{2}\)
\(C=\dfrac{4}{9}\cdot1+\dfrac{2}{9}\)
\(C=\dfrac{4}{9}+\dfrac{2}{9}\)
\(C=\dfrac{4+2}{9}\)
\(C=\dfrac{6}{9}\)
\(C=\dfrac{2}{3}\)
\(D=\dfrac{8}{19}\cdot\dfrac{5}{11}+\dfrac{7}{11}\cdot\dfrac{8}{19}+\dfrac{12}{11}\cdot\dfrac{11}{19}\)
\(D=\dfrac{8}{19}\cdot\left(\dfrac{5}{11}+\dfrac{7}{11}\right)+\dfrac{12}{11}\cdot\dfrac{11}{19}\)
\(D=\dfrac{8}{19}\cdot\dfrac{12}{11}+\dfrac{12}{11}\cdot\dfrac{11}{19}\)
\(D=\dfrac{12}{11}\cdot\left(\dfrac{8}{19}+\dfrac{11}{19}\right)\)
\(D=\dfrac{12}{11}\cdot\dfrac{19}{19}\)
\(D=\dfrac{12}{11}\cdot1\)
\(D=\dfrac{12}{11}\)
29 tháng 10 2023
a: \(\dfrac{5}{6}\cdot7=\dfrac{5\cdot7}{6}=\dfrac{35}{6}\)
b: \(\dfrac{7}{10}\cdot3=\dfrac{7\cdot3}{10}=\dfrac{21}{10}\)
c: \(5\cdot\dfrac{4}{21}=\dfrac{5\cdot4}{21}=\dfrac{20}{21}\)
d: \(2\cdot\dfrac{5}{9}=\dfrac{2\cdot5}{9}=\dfrac{10}{9}\)
27 tháng 7 2018
a. = 1/20 + 5 - 1/2
= 101/20 - 1/2
= 91/20
b. = ( 6/15 - 3/5) - ( 7/8 + 2/16) + 3
= -1/5 - 1 + 3
= 9/5
c. = 15/7 . ( 3/5 - 8/5)
= 15/7 . ( -1)
= - 15/7
e. = -14/9 - 3/9
= -17/9
f. = 19/21 . ( 15/17 + 2/17) + 13/21
= 19/21 . 1 + 13/21
= 32/21
g. = 43/12 : 2 + 5/24
= 43/24 + 5/24
= 2
22 tháng 2 2022
a: =27/45-20/45=7/45
b: \(=\dfrac{3}{5}+\dfrac{30}{40}=\dfrac{3}{5}+\dfrac{3}{4}=\dfrac{12}{20}+\dfrac{15}{20}=\dfrac{27}{20}\)
c: \(=\dfrac{8}{13}\left(\dfrac{7}{2}-\dfrac{5}{2}+1\right)=\dfrac{8}{13}\cdot2=\dfrac{16}{13}\)
d: \(=\dfrac{9}{23}\left(\dfrac{5}{17}-\dfrac{22}{17}\right)+11+\dfrac{9}{23}=11\)
R
22 tháng 2 2022
a) \(\dfrac{3}{5}+\dfrac{-4}{9}=\dfrac{27}{45}+\dfrac{-20}{45}=\dfrac{7}{45}\)
b) \(\dfrac{3}{5}+\dfrac{2}{5}.\dfrac{15}{8}=1.\dfrac{15}{8}=\dfrac{15}{8}\)
c) \(\dfrac{7}{2}.\dfrac{8}{13}+\dfrac{8}{13}.\dfrac{-5}{2}+\dfrac{8}{13}=\dfrac{8}{13}.\left(\dfrac{7}{2}+\dfrac{-5}{2}\right)=\dfrac{8}{13}.1=\dfrac{8}{13}\)
d) \(\dfrac{-5}{17}.\dfrac{-9}{23}+\dfrac{9}{23}.\dfrac{-22}{17}+11\dfrac{9}{23}=\dfrac{9}{23}.\left(\dfrac{-5}{17}+\dfrac{-22}{17}\right)=\dfrac{-243}{391}\)
11 tháng 4 2023
\(=2-\left(\dfrac{5}{3}-\dfrac{7}{6}+\dfrac{9}{10}-...-\dfrac{19}{45}\right)\)
\(=2-2\left(\dfrac{5}{6}-\dfrac{7}{12}+\dfrac{9}{20}-...-\dfrac{19}{90}\right)\)
\(=2-2\left(\dfrac{1}{2}+\dfrac{1}{3}-\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}+\dfrac{1}{5}-...-\dfrac{1}{9}-\dfrac{1}{10}\right)\)
\(=2-2\cdot\dfrac{4}{10}=2-\dfrac{8}{10}=2-\dfrac{4}{5}=\dfrac{6}{5}\)
GL
24 tháng 8 2023
a) \(\dfrac{4}{24}+\dfrac{7}{6}=\dfrac{4}{24}+\dfrac{28}{24}=\dfrac{4+28}{24}=\dfrac{32}{24}=\dfrac{4}{3}\)
b) \(\dfrac{10}{15}-\dfrac{1}{3}=\dfrac{10}{15}-\dfrac{5}{15}=\dfrac{10-5}{15}=\dfrac{5}{15}=\dfrac{1}{3}\)
c) \(\dfrac{21}{28}-\dfrac{1}{4}=\dfrac{21}{28}-\dfrac{7}{28}=\dfrac{21-7}{28}=\dfrac{14}{28}=\dfrac{1}{2}\)
d) \(\dfrac{35}{40}+\dfrac{5}{8}=\dfrac{35}{40}+\dfrac{25}{40}=\dfrac{35+25}{40}=\dfrac{60}{40}=\dfrac{3}{2}\)
24 tháng 8 2023
\(a)\dfrac{4}{24}=\dfrac{1}{6} \\ \dfrac{1}{6}+\dfrac{7}{6}\\ =\dfrac{8}{6}=\dfrac{4}{3}\\ b)\dfrac{10}{15}=\dfrac{2}{3}-\dfrac{1}{3}\\ =\dfrac{1}{3}\\ c)\dfrac{21}{28}=\dfrac{3}{4}\\ \dfrac{3}{4}-\dfrac{1}{4}\\ =\dfrac{2}{4}=\dfrac{1}{2}\\ d)\dfrac{35}{40}=\dfrac{7}{8}\\ \dfrac{7}{8}+\dfrac{5}{8}\\ =\dfrac{12}{8}=\dfrac{3}{2}\)
H
24 tháng 8 2023
a)
\(\dfrac{7}{24}+\dfrac{11}{6}\\ =\dfrac{7}{24}+\dfrac{11\times4}{6\times4}\\ =\dfrac{7}{24}+\dfrac{44}{24}\\ =\dfrac{7+44}{24}\\ =\dfrac{51}{24}\\=\dfrac{17}{8}\)
b)
\(3+\dfrac{5}{8}\\ =\dfrac{3\times8}{8}+\dfrac{5}{8}\\ =\dfrac{24}{8}+\dfrac{5}{8}\\ =\dfrac{29}{8}\)
c)
\(\dfrac{19}{28}-\dfrac{3}{7}\\ =\dfrac{19}{28}-\dfrac{3\times4}{7\times4}\\ =\dfrac{19}{28}-\dfrac{12}{28}\\ =\dfrac{7}{28}=\dfrac{1}{4}\)
d)
\(\dfrac{53}{21}-1\\ =\dfrac{53}{21}-\dfrac{21}{21}\\ =\dfrac{53-21}{21}\\ =\dfrac{32}{21}\)
GL
24 tháng 8 2023
a) \(\dfrac{7}{24}+\dfrac{11}{6}=\dfrac{7}{24}+\dfrac{44}{24}=\dfrac{7+44}{24}=\dfrac{51}{24}\)
b) \(3+\dfrac{5}{8}=\dfrac{24}{8}+\dfrac{5}{8}=\dfrac{24+5}{8}=\dfrac{29}{8}\)
c) \(\dfrac{19}{28}-\dfrac{3}{7}=\dfrac{19}{28}-\dfrac{12}{28}=\dfrac{19-12}{28}=\dfrac{7}{28}=\dfrac{1}{4}\)
d) \(\dfrac{53}{21}-1=\dfrac{53}{21}-\dfrac{21}{21}=\dfrac{53-21}{21}=\dfrac{32}{21}\)
\(a)\dfrac{5}{7}\times\dfrac{7}{15}\\ =\dfrac{5\times7}{7\times15}\\ =\dfrac{35}{105}=\dfrac{1}{3}\\ b)\dfrac{8}{21}\times3\\ =\dfrac{8\times3}{21}\\ =\dfrac{24}{21}=\dfrac{8}{7}\\ c)\dfrac{24}{17}:\dfrac{9}{17}\\ =\dfrac{24}{17}\times\dfrac{17}{9}\\ =\dfrac{24\times17}{17\times9}\\ =\dfrac{408}{153}=\dfrac{8}{3}\\ d)\dfrac{36}{5}:9\\ =\dfrac{36}{5}\times\dfrac{1}{9}\\ =\dfrac{36\times1}{5\times9}\\ =\dfrac{36}{45}=\dfrac{4}{5}\)
a) \(\dfrac{5}{7}\times\dfrac{7}{15}=\dfrac{5\times7}{7\times15}=\dfrac{35}{105}=\dfrac{1}{3}\)
b) \(\dfrac{8}{21}\times3=\dfrac{8\times3}{21}=\dfrac{24}{21}=\dfrac{8}{7}\)
c) \(\dfrac{24}{17}:\dfrac{9}{17}=\dfrac{24}{17}\times\dfrac{17}{9}=\dfrac{24\times17}{17\times9}=\dfrac{24}{9}=\dfrac{8}{3}\)
d) \(\dfrac{36}{5}:9=\dfrac{36}{5}\times\dfrac{1}{9}=\dfrac{36}{5\times9}=\dfrac{36}{45}=\dfrac{4}{5}\)