a (6/11+5/11) ×3/7 b (6/7-4/7) : 2/5
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AT
26 tháng 9 2021
a) -6 . (- \(\dfrac{2}{3}\) ) . 0,25 = 14 . 0,25 = 3,5
b) -\(\dfrac{15}{4}\) . ( - \(\dfrac{7}{15}\) ) . ( - \(\dfrac{22}{25}\) ) = \(\dfrac{7}{4}\) . ( - \(\dfrac{22}{25}\) ) = - \(\dfrac{77}{50}\) = - 1,54
c) -\(\dfrac{21}{5}\) . ( - \(\dfrac{9}{11}\) ) . ( - \(\dfrac{11}{14}\) ) . \(\dfrac{2}{5}\) = \(\dfrac{189}{55}\) . ( - \(\dfrac{11}{14}\) ) . \(\dfrac{2}{5}\) = - \(\dfrac{297}{110}\) . \(\dfrac{2}{5}\) = - \(\dfrac{297}{275}\)
K
9 tháng 3 2022
\(\dfrac{3}{5}+\dfrac{4}{3}\times\dfrac{5}{6}=\dfrac{3}{5}+\dfrac{10}{9}=\dfrac{27}{45}+\dfrac{50}{45}=\dfrac{77}{45}\)
\(2-\dfrac{7}{6}+\dfrac{1}{3}=\dfrac{12}{6}-\dfrac{7}{6}+\dfrac{2}{6}=\dfrac{7}{6}\)
\(\dfrac{7}{6}\times3-\dfrac{3}{5}=\dfrac{7}{2}-\dfrac{3}{5}=\dfrac{35}{10}-\dfrac{6}{10}=\dfrac{29}{10}\)
C
4 tháng 5 2022
a, 2/3 - 2/9 + 7/9 = 6/9 - 2/9 + 7/9 = 10/9
b, 7/6 + 3/5 : 6 = 7/6 + 3/5 x 1/6 = 7/6 + 1/10 = 70/60 + 6/10 = 76/10 = 38/5
c, x : 6/25 = 18
x = 18 x 6/25
x = 36/25
d, ( 2/5 + 4/7) : x = 17/5
29/35 : x = 17/5
x = 29/35 : 17/5
x = 29/119
4 tháng 5 2022
\(a.\dfrac{2}{3}-\dfrac{2}{9}+\dfrac{7}{9}=\dfrac{6}{9}-\dfrac{2}{9}+\dfrac{7}{9}=\dfrac{4}{9}+\dfrac{7}{9}=\dfrac{11}{9}\\ b.\dfrac{7}{6}+\dfrac{3}{5}:6=\dfrac{7}{6}+\dfrac{3}{5}\times\dfrac{1}{6}=\dfrac{7}{6}+\dfrac{1}{10}=\dfrac{70}{60}+\dfrac{6}{60}=\dfrac{76}{60}=\dfrac{19}{15}\\ c.x:\dfrac{6}{25}=18\\ x=18\times\dfrac{6}{25}\\ x=\dfrac{108}{25}\\ d.\left(\dfrac{2}{5}+\dfrac{4}{7}\right):x=\dfrac{17}{5}\\ \dfrac{34}{35}:x=\dfrac{7}{5}\\ x=\dfrac{34}{35}:\dfrac{7}{5}\\ x=\dfrac{34}{49}\)
HK
2
H
23 tháng 2 2023
`a, 2/7 +(3/7 + 5/7)= 2/7 + 3/7 + 5/7=(2/7 +5/7)+3/7= 1+3/7=7/7+3/7=10/7`
`b, (6/11+5/11)+4/11= 11/11+4/11=15/11`
`c, (5/6 + 7/6)+2/6= 12/6 + 2/6= 14/6= 7/3`
`@ yl`
23 tháng 2 2023
\(a\) \(\dfrac{2}{7}+\left(\dfrac{3}{7}+\dfrac{5}{7}\right)=\dfrac{2}{7}+\dfrac{8}{7}=\dfrac{10}{7}\)
\(b\) \(\left(\dfrac{6}{11}+\dfrac{5}{11}\right)+\dfrac{4}{11}=\dfrac{11}{11}+\dfrac{4}{11}=\dfrac{15}{11}\)
\(c\) \(\left(\dfrac{5}{6}+\dfrac{7}{6}\right)+\dfrac{2}{6}=\dfrac{12}{6}+\dfrac{2}{6}=\dfrac{14}{6}=\dfrac{7}{3}\)
13 tháng 5 2017
d)\(\frac{2}{3.5}+\frac{2}{5.7}+....+\frac{2}{97.99}\)
\(=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+....+\frac{1}{97}-\frac{1}{99}\)
\(=\frac{1}{3}-\frac{1}{99}\)
\(=\frac{32}{99}\)
13 tháng 5 2017
a) 11/4x(-0,4)x-1,6x11/4
= -1,1 x-1,6x11/4
= 1,76x11/4
= 4,48
b) 6/19x-7/11+6/19x-4/19x-4/11+13/19
= -42/209+96/3971+13/19
= -702/3971+13/19
= 2015/3971
c) 2/5x3/7+-3/7x3/5+3/7
= 3/7x(2/5+3/5+1)
= 3/7x(1+1)
= 3/7x2
= 6/7
d) 2/3x5+2x5/7+2/7x9+....+2/97x99
= 1/3-1/5+1/5-1/7+1/7-1/9+......+1/97-1/99
= 1/3-1/99
= 32/99
a: =11/11x3/7=3/7
b: =2/7x5/2=5/7
\(a,\left(\dfrac{6}{11}+\dfrac{5}{11}\right)\times\dfrac{3}{7}=\dfrac{11}{11}\times\dfrac{3}{7}=1\times\dfrac{3}{7}=\dfrac{3}{7}\\ b,\left(\dfrac{6}{7}-\dfrac{4}{7}\right):\dfrac{2}{5}=\dfrac{2}{7}\times\dfrac{5}{2}=\dfrac{5}{7}\)