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4 tháng 3 2022
a: \(=\dfrac{-7}{8}\left(\dfrac{3}{5}+\dfrac{2}{5}\right)+3+\dfrac{7}{8}=\dfrac{-7}{8}+\dfrac{7}{8}+3=3\)
b: \(=-\dfrac{8}{5}:\dfrac{5}{3}=-\dfrac{24}{25}\)
c: \(=\dfrac{6}{7}+\dfrac{1}{8}-\dfrac{3}{4}=\dfrac{6}{7}+\dfrac{1}{8}-\dfrac{6}{8}=\dfrac{6}{7}-\dfrac{5}{8}=\dfrac{48}{56}-\dfrac{35}{56}=\dfrac{13}{56}\)
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) \(\dfrac{-5}{17}.\dfrac{-9}{23}+\dfrac{9}{23}.\dfrac{-22}{17}+11\dfrac{9}{23}=\dfrac{9}{23}.\left(\dfrac{-5}{17}+\dfrac{-22}{17}\right)=\dfrac{-243}{391}\)
18 tháng 2 2022
-6/8=-3/2
2/7
Quy đồng được 12/20+-35/20=-23/20
Quy đồng được -10/15+3/15=-7/15
Quy đồng lên được -4/26+-5/26=-9/26
Quy đồng lên được: -12/21+7/21=-5/21 nhé
R
18 tháng 2 2022
\(\dfrac{-1}{8}+\dfrac{-5}{8}=\dfrac{-6}{8}=\dfrac{-3}{4}\)
\(\dfrac{-3}{7}+\dfrac{5}{7}=\dfrac{2}{7}\)
\(\dfrac{3}{5}+\dfrac{-7}{4}=\dfrac{12}{20}+\dfrac{-35}{20}=\dfrac{-23}{20}\)
\(\dfrac{-2}{3}+\dfrac{1}{5}=\dfrac{-10}{15}+\dfrac{3}{15}=\dfrac{-13}{15}\)
\(\dfrac{2}{13}+\dfrac{-5}{26}=\dfrac{-4}{26}+\dfrac{-5}{26}=\dfrac{-9}{26}\)
\(\dfrac{-4}{7}+\dfrac{1}{3}=\dfrac{-12}{21}+\dfrac{7}{21}=\dfrac{-5}{21}\)
VD
23 tháng 3 2022
\(c,\dfrac{-3}{8}.\dfrac{2}{5}+\dfrac{-3}{8}.\dfrac{14}{5}\\ =\dfrac{-3}{8}.\left(\dfrac{2}{5}+\dfrac{14}{5}\right)\\ =\dfrac{-3}{8}.\dfrac{16}{5}\\ =\dfrac{-6}{5}\\ d,\left(\dfrac{1}{4}+\dfrac{11}{9}\right):\dfrac{34}{5}+\left(\dfrac{-2}{9}+\dfrac{29}{4}\right):\dfrac{34}{5}\\ =\left(\dfrac{1}{4}+\dfrac{11}{9}\right).\dfrac{5}{34}+\left(\dfrac{-2}{9}+\dfrac{29}{4}\right).\dfrac{5}{34}\\ =\left(\dfrac{1}{4}+\dfrac{11}{9}+\dfrac{-2}{9}+\dfrac{29}{4}\right).\dfrac{5}{34}\\ =\left[\left(\dfrac{1}{4}+\dfrac{29}{4}\right)+\left(\dfrac{11}{9}+\dfrac{-2}{9}\right)\right].\dfrac{5}{34}\\ =\left(\dfrac{15}{2}+1\right).\dfrac{5}{34}\\ =\dfrac{17}{2}.\dfrac{5}{34}\\ =\dfrac{5}{4}\)
23 tháng 3 2022
c) \(\dfrac{-3}{8}.\dfrac{2}{5}+\dfrac{-3}{8}.\dfrac{14}{5}\)
\(=\dfrac{-3}{8}.\left(\dfrac{2}{5}+\dfrac{14}{5}\right)\)
\(=\dfrac{-3}{8}.\dfrac{16}{5}\)
\(=\dfrac{-6}{5}\)
Giải thích rút gọn 16 cho 8 được 2
DT
Dang Tung
CTVHS
14 tháng 6 2023
\(\dfrac{\dfrac{2}{3}-\dfrac{2}{5}+\dfrac{2}{7}}{\dfrac{8}{3}-\dfrac{8}{5}+\dfrac{8}{7}}=\dfrac{2\left(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{7}\right)}{8\left(\dfrac{1}{3}-\dfrac{1}{5}+\dfrac{1}{7}\right)}\\ =\dfrac{2}{8}=\dfrac{1}{4}\)
PP
Phùng Phạm Quỳnh Trang
CTVHS
14 tháng 6 2023
2/3 - 2/5 + 2/7
= 70/105 - 42/105 + 20/105
= (70 - 42 + 20) / 105
= 48 / 105
= 16/35
8/3 - 8/5 + 8/7
= 280/105 - 168 / 105 + 120/105
= ( 280 - 168 + 120 ) / 105
= 232/105
9 tháng 3 2022
g: \(=\dfrac{-3}{4}-\dfrac{1}{4}+\dfrac{5}{7}+\dfrac{2}{7}+\dfrac{3}{5}=\dfrac{3}{5}\)
h: \(=\dfrac{7}{19}\left(\dfrac{8}{11}+\dfrac{3}{11}\right)-\dfrac{12}{19}=\dfrac{7}{19}-\dfrac{12}{19}=-\dfrac{5}{19}\)
i: \(=\dfrac{2013}{7}\left(19+\dfrac{5}{8}-26-\dfrac{5}{8}\right)=\dfrac{2013}{7}\cdot\left(-7\right)=-2013\)
TA
23 tháng 7 2021
`8/5 .2/3 + (-5.5)/(3.5) = 16/15 - 5/3 = -3/5`
b) 6/7+5/8 :5 -3/16 .(-2)^2=6/7 + 1/8 - 3/16 .4`
`=55/56 - 3/4`
`=13/56`
H
23 tháng 7 2021
\(a,\dfrac{8}{5}.\dfrac{2}{3}+\dfrac{-5.5}{3.5}=\dfrac{16}{15}+\dfrac{-25}{15}=-\dfrac{9}{15}=-\dfrac{3}{5}\)
\(b,\dfrac{6}{7}+\dfrac{5}{8}:5-\dfrac{3}{16}\left(-2\right)^2=\dfrac{6}{7}+\dfrac{5}{8}:5-\dfrac{3}{16}.4=\dfrac{6}{7}+\dfrac{1}{8}-\dfrac{3}{4}=\dfrac{55}{56}-\dfrac{3}{4}=\dfrac{13}{56}\)
\(\dfrac{5}{8}\left(-\dfrac{2}{5}+\dfrac{3}{5}\right)=\dfrac{5}{8}\times\dfrac{1}{5}=\dfrac{1}{8}\)
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