Tính bằng cách hợp lý
a)\(\dfrac{7}{15}\)-(\(\dfrac{2}{15}\)-\(\dfrac{12}{18}\))
b) (\(\dfrac{7}{41}\)-\(\dfrac{4}{9}\))-(\(\dfrac{3}{19}\)+\(\dfrac{7}{41}\))+(\(\dfrac{4}{9}\)-\(\dfrac{16}{19}\))
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Thực hiện phép tính (bằng cách hợp lý nếu có thể)
a) \(1\dfrac{4}{23}+\dfrac{5}{21}-\dfrac{4}{23}+0,5+\dfrac{16}{21}\)
b) \(\dfrac{3}{7}.19\dfrac{1}{3}-\dfrac{3}{7}.33\dfrac{1}{3}\)
c) \(9.\left(-\dfrac{1}{3}\right)^3+\dfrac{1}{3}\)
d) \(15\dfrac{1}{4}:\left(-\dfrac{5}{7}\right)-25\dfrac{1}{4}\left(-\dfrac{5}{7}\right)\)
bài 1 tính :dfrac{-8}{9} . dfrac{12}{19} . dfrac{9}{-4} . dfrac{19}{24} dfrac{-5}{16} . dfrac{17}{15} : dfrac{-17}{8} dfrac{4}{13} . dfrac{2}{7} + dfrac{-3}{26} + dfrac{4}{13} . dfrac{5}{7} dfrac{6}{11} . dfrac{3}{4} + dfrac{-12}{60} +dfrac{-3}{4} .dfrac{-5}{11}
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bài 1 tính :
\(\dfrac{-8}{9}\) . \(\dfrac{12}{19}\) . \(\dfrac{9}{-4}\) . \(\dfrac{19}{24}\) \(\dfrac{-5}{16}\) . \(\dfrac{17}{15}\) : \(\dfrac{-17}{8}\)
\(\dfrac{4}{13}\) . \(\dfrac{2}{7}\) + \(\dfrac{-3}{26}\) + \(\dfrac{4}{13}\) . \(\dfrac{5}{7}\) \(\dfrac{6}{11}\) . \(\dfrac{3}{4}\) + \(\dfrac{-12}{60}\) +\(\dfrac{-3}{4}\) .\(\dfrac{-5}{11}\)
giúp mk vs mn ơi , mai cô giáo ktra mk r
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a: \(=\dfrac{8}{9}\cdot\dfrac{9}{4}\cdot\dfrac{12}{19}\cdot\dfrac{19}{24}=\dfrac{1}{2}\cdot2=1\)
b: \(=\dfrac{5}{16}\cdot\dfrac{17}{15}\cdot\dfrac{8}{17}=\dfrac{5}{16}\cdot\dfrac{8}{15}=\dfrac{40}{240}=\dfrac{1}{6}\)
c: \(=\dfrac{4}{13}\left(\dfrac{2}{7}+\dfrac{5}{7}\right)-\dfrac{3}{26}=\dfrac{4}{13}-\dfrac{3}{26}=\dfrac{5}{26}\)
c: \(=\dfrac{3}{4}\left(\dfrac{6}{11}+\dfrac{5}{11}\right)-\dfrac{1}{5}=\dfrac{3}{4}-\dfrac{1}{5}=\dfrac{11}{20}\)
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Tính giá trị các biểu thức sau một cách hợp lí :
\(A=\dfrac{7}{19}.\dfrac{8}{11}+\dfrac{7}{19}.\dfrac{3}{11}+\dfrac{12}{19}\)
\(B=\dfrac{5}{9}.\dfrac{7}{13}+\dfrac{5}{9}.\dfrac{9}{13}-\dfrac{5}{9}.\dfrac{3}{13}\)
\(C=\left(\dfrac{67}{111}+\dfrac{2}{33}-\dfrac{15}{117}\right).\left(\dfrac{1}{3}-\dfrac{1}{4}-\dfrac{1}{12}\right)\)
Gợi ý: Sử dụng tính chất phân phối của phép nhân đối với phép cộng để nhóm thừa số chung ra ngoài.
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12 tháng 3 2022 lúc 14:25
Tính bằng cách hợp lý:a,dfrac{2}{3}+left(dfrac{5}{7}+dfrac{-2}{3}right) b,left(dfrac{-1}{4}+dfrac{5}{8}right)+dfrac{-3}{8}c,dfrac{7}{5}.dfrac{8}{19}+dfrac{7}{5}.dfrac{12}{19}-dfrac{7}{5}.dfrac{1}{19}d,6dfrac{3}{10}-left(3dfrac{4}{7}+2dfrac{3}{10}right)e,left(31,12-5,97right)-left(-68,88+4,03right)h,3,7.left(-10,56right)+3,7.110,56
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Tính bằng cách hợp lý:
\(a,\dfrac{2}{3}+\left(\dfrac{5}{7}+\dfrac{-2}{3}\right)\)
\(b,\left(\dfrac{-1}{4}+\dfrac{5}{8}\right)+\dfrac{-3}{8}\)
\(c,\dfrac{7}{5}.\dfrac{8}{19}+\dfrac{7}{5}.\dfrac{12}{19}-\dfrac{7}{5}.\dfrac{1}{19}\)
\(d,6\dfrac{3}{10}-\left(3\dfrac{4}{7}+2\dfrac{3}{10}\right)\)
\(e,\left(31,12-5,97\right)-\left(-68,88+4,03\right)\)
\(h,3,7.\left(-10,56\right)+3,7.110,56\)
1. a) dfrac{5}{3} . dfrac{11}{7} - dfrac{5}{7} . dfrac{5}{3}b) (0,125)^{16}. (-8)^{16}c) dfrac{9^2.9^3}{3^9}d) dfrac{9}{24} - dfrac{7}{41} + dfrac{15}{24} + 0,75 - dfrac{34}{41}e) 5dfrac{2}{7} . ( -dfrac{1}{3}) - 2dfrac{2}{7} . (-dfrac{1}{3})2. a) dfrac{3}{4} + dfrac{2}{3}x dfrac{1}{2}b) (2x - 1)^2 25c) | x + 5 | - 6 9
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1. a) \(\dfrac{5}{3}\) . \(\dfrac{11}{7}\) - \(\dfrac{5}{7}\) . \(\dfrac{5}{3}\)
b) (0,125)\(^{16}\). (-8)\(^{16}\)
c) \(\dfrac{9^2.9^3}{3^9}\)
d) \(\dfrac{9}{24}\) - \(\dfrac{7}{41}\) + \(\dfrac{15}{24}\) + 0,75 - \(\dfrac{34}{41}\)
e) \(5\dfrac{2}{7}\) . ( \(-\dfrac{1}{3}\)) - \(2\dfrac{2}{7}\) . (\(-\dfrac{1}{3}\))
2. a) \(\dfrac{3}{4}\) + \(\dfrac{2}{3}x\) = \(\dfrac{1}{2}\)
b) (2x - 1)\(^2\) = 25
c) | x + 5 | - 6 = 9
1.
a)10/7
b) 1
c) 3
d) 3/4
e) -1
2.
a)-3/8
b)x= 3 và x=-2
c)x=10 và x=-20
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Bài 1.( 2 điểm)Tính bằng cách hợp lí:a) dfrac{1}{2}+dfrac{9}{10}+dfrac{5}{6}-dfrac{11}{14}-dfrac{1}{3}+dfrac{-4}{35}b) left(dfrac{18}{23}+dfrac{7}{12}right)+left(dfrac{-13}{19}-dfrac{3}{4}right)+left(dfrac{-6}{19}+dfrac{5}{23}right)c) dfrac{4}{3}+dfrac{-5}{6}+dfrac{-1}{4}d) dfrac{5}{6}-dfrac{7}{5}+dfrac{17}{30}
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Bài 1.( 2 điểm)Tính bằng cách hợp lí:
a) \(\dfrac{1}{2}+\dfrac{9}{10}+\dfrac{5}{6}-\dfrac{11}{14}-\dfrac{1}{3}+\dfrac{-4}{35}\)
b) \(\left(\dfrac{18}{23}+\dfrac{7}{12}\right)+\left(\dfrac{-13}{19}-\dfrac{3}{4}\right)+\left(\dfrac{-6}{19}+\dfrac{5}{23}\right)\)
c) \(\dfrac{4}{3}+\dfrac{-5}{6}+\dfrac{-1}{4}\)
d) \(\dfrac{5}{6}-\dfrac{7}{5}+\dfrac{17}{30}\)
1: \(\dfrac{1}{2}+\dfrac{9}{10}+\dfrac{5}{6}-\dfrac{11}{14}-\dfrac{1}{3}+\dfrac{-4}{35}\)
\(=\left(\dfrac{1}{2}+\dfrac{5}{6}-\dfrac{1}{3}\right)+\dfrac{9}{10}-\left(\dfrac{11}{14}+\dfrac{4}{35}\right)\)
\(=\dfrac{3+5-2}{6}+\dfrac{9}{10}-\dfrac{55+8}{70}\)
\(=1+\dfrac{9}{10}-\dfrac{9}{10}\)
=1
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Tính nhanh :
\(A=\dfrac{5}{13}+\dfrac{-5}{7}+\dfrac{-20}{41}+\dfrac{8}{13}+\dfrac{-21}{41};B=\dfrac{-5}{9}+\dfrac{8}{15}+\dfrac{-2}{11}+\dfrac{4}{-9}+\dfrac{7}{15}\)
1, dfrac{-5}{7} . dfrac{2}{11} + dfrac{-5}{7} . dfrac{9}{11} + 1dfrac{5}{7}
2,-3dfrac{4}{13} . 15dfrac{3}{41} + 3dfrac{4}{13} . 2dfrac{3}{41}
3, dfrac{4}{5} . 15dfrac{1}{4} - dfrac{4}{5} . 15dfrac{1}{3} + dfrac{11}{30}
4,dfrac{4}{20} + dfrac{16}{42} + dfrac{6}{15} - dfrac{3}{5} + dfrac{2}{21} - dfrac{10}{21} + dfrac{3}{10}
Giúp mik nha. Cảm ơn
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1, \(\dfrac{-5}{7}\) . \(\dfrac{2}{11}\) + \(\dfrac{-5}{7}\) . \(\dfrac{9}{11}\) + \(1\dfrac{5}{7}\)
2,\(-3\dfrac{4}{13}\) . \(15\dfrac{3}{41}\) + \(3\dfrac{4}{13}\) . \(2\dfrac{3}{41}\)
3, \(\dfrac{4}{5}\) . \(15\dfrac{1}{4}\) - \(\dfrac{4}{5}\) . \(15\dfrac{1}{3}\) + \(\dfrac{11}{30}\)
4,\(\dfrac{4}{20}\) + \(\dfrac{16}{42}\) + \(\dfrac{6}{15}\) - \(\dfrac{3}{5}\) + \(\dfrac{2}{21}\) - \(\dfrac{10}{21}\) + \(\dfrac{3}{10}\)
Giúp mik nha. Cảm ơn
Bài 2: Tính hợp lý:
\(A=\dfrac{63636337-37373763}{1+2+3+...+2006}\)
\(B=1\dfrac{6}{41}\left(\dfrac{12+\dfrac{12}{19}-\dfrac{12}{37}-\dfrac{12}{53}}{3+\dfrac{1}{3}-\dfrac{3}{37}-\dfrac{3}{53}}:\dfrac{4+\dfrac{4}{17}+\dfrac{4}{19}+\dfrac{4}{2006}}{5+\dfrac{5}{17}+\dfrac{5}{19}+\dfrac{5}{2006}}\right)\dfrac{124242423}{237373735}\)
\(A=\dfrac{636363\cdot37-373737\cdot63}{1+2+3+...+2006}\)
\(=\dfrac{37^2\cdot3^3\cdot7^2\cdot13-37^2\cdot3^3\cdot7^2\cdot13}{\left(2006+1\right)\cdot1003}\)
=0
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