tính
\(\dfrac{-21}{10}+\dfrac{21}{10}.\dfrac{3}{4}-\dfrac{3}{4}\)
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tính
\(\dfrac{-21}{10}+\dfrac{21}{10}.\dfrac{3}{4}-\dfrac{3}{4}\)
Thực hiện phép tính ( tính nhanh nếu có thể ) a, -5/21 + -2/21 + 8/24b, 4/11 . -2/7 + 4/11 . -4/7 + 4/11 . -1/7c, 10dfrac{5}{9} - ( 3dfrac{5}{7} + 4dfrac{5}{9} )d, 1/3 + 1dfrac{3}{4} - ( 1dfrac{3}{4} - 80% )e, 5dfrac{3}{5} + 7dfrac{21}{48} : 10/7 - 5dfrac{21}{48} : 10/7f, -5/7 . 2/11 - 5/11 . 9/7 + 2dfrac{5}{7}g, -3/13 . 6/8 + 7/13 . -3/8 + 1dfrac{3}{8}
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Thực hiện phép tính ( tính nhanh nếu có thể )
a, -5/21 + -2/21 + 8/24
b, 4/11 . -2/7 + 4/11 . -4/7 + 4/11 . -1/7
c, \(10\dfrac{5}{9}\) - ( \(3\dfrac{5}{7}\) + \(4\dfrac{5}{9}\) )
d, 1/3 + \(1\dfrac{3}{4}\) - ( \(1\dfrac{3}{4}\) - 80% )
e, \(5\dfrac{3}{5}\) + \(7\dfrac{21}{48}\) : 10/7 - \(5\dfrac{21}{48}\) : 10/7
f, -5/7 . 2/11 - 5/11 . 9/7 + \(2\dfrac{5}{7}\)
g, -3/13 . 6/8 + 7/13 . -3/8 + \(1\dfrac{3}{8}\)
a: =-1/3+1/3=0
b: \(=\dfrac{4}{11}\left(-\dfrac{2}{7}-\dfrac{4}{7}-\dfrac{1}{7}\right)=\dfrac{4}{11}\cdot\left(-1\right)=-\dfrac{4}{11}\)
c: \(=10+\dfrac{5}{9}-3-\dfrac{5}{7}-4-\dfrac{5}{9}=3-\dfrac{5}{7}=\dfrac{16}{7}\)
d: \(=\dfrac{1}{3}+\dfrac{7}{4}-\dfrac{7}{4}+\dfrac{4}{5}=\dfrac{1}{3}+\dfrac{4}{5}=\dfrac{5+12}{15}=\dfrac{17}{15}\)
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a: =-1/3+1/3=0
b: =10+59−3−57−4−59=3−57=167=10+59−3−57−4−59=3−57=167
d:
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12+3/7-11+3/7 tính bằng cách thuận tiện nhé
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Tính hợp lí
1) (dfrac{7}{-18}+dfrac{-5}{12}) -dfrac{13}{-18}
2) dfrac{-13}{17}+(dfrac{13}{-21}+dfrac{-4}{17})
3) ( dfrac{13}{-10}-dfrac{-4}{13})+dfrac{11}{-10}
4) dfrac{13}{17}timesdfrac{4}{-5}+dfrac{13}{17}timesdfrac{-3}{4}
5) dfrac{-5}{12}timesdfrac{7}{-17}timesdfrac{9}{-20}
6) dfrac{5}{9}timesdfrac{11}{23}+ dfrac{11}{23}timesdfrac{17}{9}-dfrac{13}{9}timesdfrac{11}{23}
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Tính hợp lí
1) \((\)\(\dfrac{7}{-18}\)+\(\dfrac{-5}{12}\)) -\(\dfrac{13}{-18}\)
2) \(\dfrac{-13}{17}\)+(\(\dfrac{13}{-21}\)+\(\dfrac{-4}{17}\))
3) ( \(\dfrac{13}{-10}\)-\(\dfrac{-4}{13}\))+\(\dfrac{11}{-10}\)
4) \(\dfrac{13}{17}\)\(\times\)\(\dfrac{4}{-5}\)+\(\dfrac{13}{17}\)\(\times\)\(\dfrac{-3}{4}\)
5) \(\dfrac{-5}{12}\)\(\times\)\(\dfrac{7}{-17}\)\(\times\)\(\dfrac{9}{-20}\)
6) \(\dfrac{5}{9}\)\(\times\)\(\dfrac{11}{23}\)+ \(\dfrac{11}{23}\)\(\times\)\(\dfrac{17}{9}\)\(-\)\(\dfrac{13}{9}\)\(\times\)\(\dfrac{11}{23}\)
\(1.\dfrac{-7}{18}+\dfrac{-5}{12}-\dfrac{-13}{18}\text{=}\left(\dfrac{-7}{18}-\dfrac{-13}{18}\right)+\dfrac{-5}{12}\text{=}\dfrac{1}{3}+\dfrac{-5}{12}\text{=}\dfrac{-1}{12}\)
\(2.\dfrac{-13}{17}+\dfrac{-13}{21}+\dfrac{-4}{17}\text{=}\left(\dfrac{-13}{17}+\dfrac{-4}{17}\right)+\dfrac{-13}{21}\text{=}-1+\dfrac{-13}{21}\text{=}\dfrac{-34}{21}\)
\(3.\dfrac{-13}{10}-\dfrac{-4}{13}+\dfrac{-11}{10}\text{=}\dfrac{-12}{5}-\dfrac{-4}{13}\text{=}\dfrac{-136}{65}\)
\(4.\dfrac{13}{17}\times\left(\dfrac{-4}{5}+\dfrac{-3}{4}\right)\text{=}\dfrac{13}{17}\times\dfrac{-31}{20}\text{=}\dfrac{-403}{340}\)
\(5.\left(\dfrac{-5}{12}\times\dfrac{-9}{20}\right)\times\dfrac{-7}{17}\text{=}\dfrac{3}{16}\times\dfrac{-7}{17}\text{=}\dfrac{-21}{272}\)
\(6.\dfrac{11}{23}\times\left(\dfrac{5}{9}+\dfrac{17}{9}-\dfrac{13}{9}\right)\text{=}\dfrac{11}{23}\times1\text{=}\dfrac{11}{23}\)
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10 tháng 11 2021 lúc 16:36
Chọn câu trả lời đúng \(\left(2x+\dfrac{1}{5}\right)\left(-\dfrac{3}{5}x+\dfrac{4}{7}\right)=0\) thì:
A. x = \(\dfrac{-1}{10}\) hoặc x = \(\dfrac{20}{21}\)
B. x = \(\dfrac{20}{21}\)
C. x = \(-\dfrac{1}{10}\)
D. x = \(-\dfrac{20}{21}\)
19 tháng 2 2022 lúc 17:27
\(\dfrac{2}{3}.\dfrac{-5}{7}\)
\(\dfrac{-1}{3}.\dfrac{5}{9}\)
\(\dfrac{-2}{5}.\dfrac{10}{4}\)
\(\dfrac{-3}{7}.\dfrac{5}{15}\)
\(\dfrac{-7}{3}.\dfrac{9}{21}\)
a: =-10/21
b: =-5/27
c: =-20/20=-1
d: =-15/105=-1/7
e: =-63/63=-1
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\(\dfrac{10}{21}\)
\(\dfrac{5}{27}\)
\(1\)
\(\dfrac{1}{7}\)
\(1\)
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Câu 1: Tính giá trị biểu thức:
a.A=\(\left(\dfrac{136}{15}-\dfrac{28}{5}+\dfrac{62}{10}\right)\).\(\dfrac{21}{24}\)
b.B=\(\dfrac{5}{6}\)+6\(\dfrac{5}{6}\)\(\left(11\dfrac{5}{20}-9\dfrac{1}{4}\right)\):8\(\dfrac{1}{3}\)
c.C=1+3+6+10+15+...+1225.
SGK Cánh diều - Tập 2 - Trang 62
29 tháng 10 2023 lúc 23:20
Rút gọn rồi tính:
a) \(\dfrac{3}{9}\times\dfrac{5}{4}\) b) \(\dfrac{10}{15}\times\dfrac{3}{5}\) c) \(\dfrac{5}{8}\times\dfrac{4}{12}\) d) \(\dfrac{9}{27}\times\dfrac{3}{21}\)
a: \(\dfrac{3}{9}\times\dfrac{5}{4}=\dfrac{5}{4}\times\dfrac{1}{3}=\dfrac{5\times1}{4\times3}=\dfrac{5}{12}\)
b: \(\dfrac{10}{15}\times\dfrac{3}{5}=\dfrac{3}{5}\times\dfrac{2}{3}=\dfrac{3\times2}{5\times3}=\dfrac{2}{5}\)
c: \(\dfrac{5}{8}\times\dfrac{4}{12}=\dfrac{5}{8}\times\dfrac{1}{3}=\dfrac{5}{3\times8}=\dfrac{5}{24}\)
d: \(\dfrac{9}{27}\times\dfrac{3}{21}=\dfrac{1}{7}\times\dfrac{1}{3}=\dfrac{1\times1}{7\times3}=\dfrac{1}{21}\)
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a) dfrac{-21}{15}.dfrac{-10}{14} b)left(-dfrac{2}{3}right)^2 c)dfrac{-3}{4}.dfrac{-4}{5}.dfrac{16}{9} d)dfrac{-8}{3}.dfrac{5}{6} e)dfrac{16}{30}.dfrac{5}{12} f) dfrac{13}{30}.dfrac{-1}{5} g)dfrac{2}{21}.dfrac{3}{28} h)left(dfrac{-3}{4}right)^3
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a) \(\dfrac{-21}{15}\).\(\dfrac{-10}{14}\) b)\(\left(-\dfrac{2}{3}\right)^2\) c)\(\dfrac{-3}{4}\).\(\dfrac{-4}{5}\).\(\dfrac{16}{9}\) d)\(\dfrac{-8}{3}\).\(\dfrac{5}{6}\) e)\(\dfrac{16}{30}\).\(\dfrac{5}{12}\) f) \(\dfrac{13}{30}\).\(\dfrac{-1}{5}\) g)\(\dfrac{2}{21}\).\(\dfrac{3}{28}\) h)\(\left(\dfrac{-3}{4}\right)^3\)
`a, -21/15 . (-10)/14 = 210/210=1`
`b, (-2/3)^2= 4/9`
`c, (-3)/4 . (-4)/5 . 16/9= 192/180=16/15`
`d, (-8)/3 . 5/6= -40/18=-20/9`
`e, 16/30 . 5/12= 8/15 . 5/12=40/180=2/9`
`f, 13/30 . (-1)/5= -13/150`
`g, 2/21 . 3/28= 6/588= 1/98`
`h, (-3/4)^3= -27/64`
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bài 4, Tính hợp lý
b, \(\dfrac{6}{21}-\dfrac{-12}{44}+\dfrac{10}{14}-\dfrac{1}{-4}-\dfrac{18}{33}\)
=(2/7+5/7)+(3/11-6/11)+1/4
=5/4-3/11
=55/44-12/44=43/44
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