tính A=2^3+2^5+...+2^19
B=\(\dfrac{1}{3^2}+\dfrac{1}{3^3}+...+\dfrac{1}{3^{19}}\)
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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:
\(a,\dfrac{2}{3}+\left(\dfrac{5}{7}+\dfrac{-2}{3}\right)\)
\(b,\left(\dfrac{-1}{4}+\dfrac{5}{8}\right)+\dfrac{-3}{8}\)
\(c,\dfrac{7}{5}.\dfrac{8}{19}+\dfrac{7}{5}.\dfrac{12}{19}-\dfrac{7}{5}.\dfrac{1}{19}\)
\(d,6\dfrac{3}{10}-\left(3\dfrac{4}{7}+2\dfrac{3}{10}\right)\)
\(e,\left(31,12-5,97\right)-\left(-68,88+4,03\right)\)
\(h,3,7.\left(-10,56\right)+3,7.110,56\)
Thực hiện phép tính-tính nhanh giá trị biểu thức
A19dfrac{1}{4} + dfrac{1}{2}x 2dfrac{1}{3}+5,75 - dfrac{1}{6}+74
B[(dfrac{1}{3}+dfrac{1}{4})] x dfrac{12}{19}+dfrac{12}{19}] : dfrac{4}{5}-dfrac{1}{4}+2012
Cdfrac{232323}{353535}:dfrac{76x47-28}{76x46+48}
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Thực hiện phép tính-tính nhanh giá trị biểu thức
A=19\(\dfrac{1}{4}\) + \(\dfrac{1}{2}\)x 2\(\dfrac{1}{3}\)+5,75 - \(\dfrac{1}{6}\)+74
B=[(\(\dfrac{1}{3}+\dfrac{1}{4}\))] x \(\dfrac{12}{19}+\dfrac{12}{19}\)] : \(\dfrac{4}{5}-\dfrac{1}{4}+2012\)
C=\(\dfrac{232323}{353535}:\dfrac{76x47-28}{76x46+48}\)
Mới thế đã hai năm trôi qua,câu trả lời từ mọi người vẫn KO XUẤT HIỆN.
Ko biết sau này câu trả lời có xuất hiện hay ko...
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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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1.Thực hiện các phép tính sau :
a) \(-\dfrac{4}{3}.\dfrac{5}{12}+\dfrac{1}{3}.\dfrac{5}{12}\) b)\(3\dfrac{1}{5}+\left(\dfrac{2}{7}-\dfrac{7}{2}\right):\dfrac{3}{28}\)
2.Tìm x, biết:
a) 2x+19=\(^{5^2}\) b)\(-\dfrac{2}{9}x-\dfrac{1}{7}=\dfrac{4}{21}\)
1,
a, \(\left(\dfrac{-4}{3}+\dfrac{1}{3}\right).\dfrac{5}{12}\)=-\(\dfrac{5}{12}\)
b, \(\dfrac{16}{5}+\left(\dfrac{-45}{14}\right):\dfrac{3}{28}\)
=\(\dfrac{-2}{15}\)
2,
a, 2x+19=25
=>x=3
b, \(-\dfrac{2}{9}x=\dfrac{1}{3}\)
=>x=\(\dfrac{-3}{2}\)
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Bài 1:
a) Ta có: \(\dfrac{-4}{3}\cdot\dfrac{5}{12}+\dfrac{1}{3}\cdot\dfrac{5}{12}\)
\(=\dfrac{5}{12}\cdot\left(\dfrac{-4}{3}+\dfrac{1}{3}\right)\)
\(=\dfrac{-5}{12}\)
b) Ta có: \(3\dfrac{1}{5}+\left(\dfrac{2}{7}-\dfrac{7}{2}\right):\dfrac{3}{28}\)
\(=\dfrac{16}{5}+\left(\dfrac{4}{14}-\dfrac{49}{14}\right):\dfrac{3}{28}\)
\(=\dfrac{16}{5}+\dfrac{-45}{14}\cdot\dfrac{28}{3}\)
\(=\dfrac{16}{5}-30=\dfrac{-134}{5}\)
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1)
a) \(-\dfrac{4}{3}.\dfrac{5}{12}+\dfrac{1}{3}.\dfrac{5}{12}=\dfrac{5}{12}.\left(\dfrac{-4}{3}+\dfrac{1}{3}\right)=\dfrac{5}{12}.\left(-1\right)=-\dfrac{5}{12}\)
b) \(3\dfrac{1}{5}+\left(\dfrac{2}{7}-\dfrac{7}{2}\right).\dfrac{28}{3}=3+\dfrac{1}{5}-\dfrac{45}{14}.\dfrac{28}{3}\)
\(=3+\dfrac{1}{5}-30=-27+\dfrac{1}{5}=-\dfrac{134}{5}\)
2)
a) \(2x+19=25\)
\(2x=25-19=6\)
\(x=3\)
b) \(-\dfrac{2}{9}x-\dfrac{1}{7}=\dfrac{4}{21}\)
\(-\dfrac{2x}{9}=\dfrac{4}{21}+\dfrac{1}{7}=\dfrac{1}{3}\)
\(x=\dfrac{1}{3}.\left(-\dfrac{9}{2}\right)=-\dfrac{3}{2}\)
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25 tháng 1 2022 lúc 16:07
a) A = \(\dfrac{19}{9}-\dfrac{-4}{11}-\dfrac{2}{-3}\)
b) B = \(\dfrac{-5}{6}+\dfrac{-7}{12}-\dfrac{1}{-5}\)
c) C = \(\dfrac{-3}{4}+\dfrac{11}{3}-\dfrac{-5}{18}\)
d) D = \(\dfrac{-19}{3}-\dfrac{4}{5}-\dfrac{-2}{3}\)
a: \(A=\dfrac{19}{9}+\dfrac{4}{11}+\dfrac{2}{3}=\dfrac{209}{99}+\dfrac{44}{99}+\dfrac{66}{99}=\dfrac{319}{99}\)
b: \(B=\dfrac{-50}{60}+\dfrac{-35}{60}+\dfrac{12}{60}=\dfrac{-73}{60}\)
c: \(C=\dfrac{-27}{36}+\dfrac{132}{36}+\dfrac{10}{36}=\dfrac{115}{36}\)
d: \(D=\dfrac{-19}{3}+\dfrac{2}{3}-\dfrac{4}{5}=\dfrac{-17}{3}-\dfrac{4}{5}=\dfrac{-85-12}{15}=-\dfrac{97}{15}\)
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bài 2: kết quả phép tính \(\dfrac{7}{19}\) x \(\dfrac{1}{3}\) + \(\dfrac{7}{19}\) x \(\dfrac{2}{3}\)=
a. \(\dfrac{14}{21}\)
b.\(\dfrac{21}{19}\)
c.\(\dfrac{14}{57}\)
d.\(\dfrac{7}{19}\)
27 tháng 1 2022 lúc 10:01
Tính giá trị biểu thứca, 19dfrac{5}{8}:dfrac{7}{12}-15dfrac{1}{4}:dfrac{7}{12} b,dfrac{2}{5}.dfrac{1}{3}-dfrac{2}{15}:dfrac{1}{5}+dfrac{3}{5}.dfrac{1}{3}c, left(3dfrac{1}{3}+2,5right):left(3dfrac{1}{6}-4dfrac{1}{5}right)-dfrac{11}{31} d, left[6+left(dfrac{1}{2}right)^3-left|-dfrac{1}{2}right|right]:dfrac{3}{12}
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Tính giá trị biểu thức
a, \(19\dfrac{5}{8}:\dfrac{7}{12}-15\dfrac{1}{4}:\dfrac{7}{12}\) b,\(\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{15}:\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}\)
c, \(\left(3\dfrac{1}{3}+2,5\right):\left(3\dfrac{1}{6}-4\dfrac{1}{5}\right)-\dfrac{11}{31}\) d, \(\left[6+\left(\dfrac{1}{2}\right)^3-\left|-\dfrac{1}{2}\right|\right]:\dfrac{3}{12}\)
a) \(=\dfrac{157}{8}.\dfrac{12}{7}-\dfrac{61}{4}.\dfrac{12}{7}=\dfrac{12}{7}\left(\dfrac{157}{8}-\dfrac{61}{4}\right)=\dfrac{12}{7}.\dfrac{35}{8}=\dfrac{15}{2}\)
b) \(\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{15}\div\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}=\dfrac{1}{3}\left(\dfrac{2}{5}+\dfrac{3}{5}\right)-\dfrac{2}{15}.5=\dfrac{1}{3}.1-\dfrac{2}{3}=\dfrac{1}{3}-\dfrac{2}{3}=-\dfrac{1}{3}\)
c) \(=-\dfrac{80}{9}\)
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a.=\(\dfrac{157}{8}:\dfrac{7}{12}-\dfrac{61}{4}:\dfrac{7}{12}=\dfrac{471}{14}-\dfrac{183}{7}=\dfrac{15}{2}\)
b.=\(\dfrac{2}{15}-\dfrac{2}{3}+\dfrac{1}{5}=-\dfrac{1}{3}\)
c.\(\left(\dfrac{10}{3}+2.5\right):\left(\dfrac{19}{6}-\dfrac{21}{5}\right)-\dfrac{11}{31}=\dfrac{35}{6}:\left(-\dfrac{31}{30}\right)-\dfrac{11}{31}=-\dfrac{175}{31}-\dfrac{11}{31}=-6\)
d.\(\left[6+\dfrac{1}{8}-\dfrac{1}{2}\right]:\dfrac{3}{12}=\dfrac{45}{8}:\dfrac{3}{12}=\dfrac{45}{2}\)
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1) Tìm x biết:
\(\left(1-\dfrac{3}{10}-x\right):\left(\dfrac{19}{10}-1-\dfrac{2}{5}\right)+\dfrac{4}{5}=1\)
2) Tính nhanh
a)\(\dfrac{1}{1.2.3}+\dfrac{1}{2.3.4}+\dfrac{1}{3.4.5}+...+\dfrac{1}{10.11.12}\)
b)\(\dfrac{1^2}{1.2}.\dfrac{2^2}{2.3}.\dfrac{3^2}{3.4}.\dfrac{4^2}{4.5}\)
câu b bài 2:
\(\dfrac{1^2}{1\cdot2}\cdot\dfrac{2^2}{2\cdot3}\cdot\dfrac{3^2}{3\cdot4}\cdot\dfrac{4^2}{4\cdot5}\)
\(=\dfrac{1}{2}\cdot\dfrac{2}{3}\cdot\dfrac{3}{4}\cdot\dfrac{4}{5}\)
\(=\dfrac{1}{5}\)
câu a bài 2:
\(\dfrac{1}{1\cdot2\cdot3}+\dfrac{1}{2\cdot3\cdot4}+\dfrac{1}{3\cdot4\cdot5}+...+\dfrac{1}{10\cdot11\cdot12}\)
\(=\dfrac{1}{1}-\dfrac{1}{2}-\dfrac{1}{3}-\dfrac{1}{2}-\dfrac{1}{3}-\dfrac{1}{4}-...-\dfrac{1}{12}\)
\(=1-\dfrac{1}{12}=\dfrac{11}{12}\)
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Bài 2: Thực hiện phép tính một cách hợp líf) dfrac{7}{19} . dfrac{8}{11} + dfrac{3}{11} . dfrac{7}{19} +dfrac{-12}{19}i) ( dfrac{3}{8} + dfrac{-3}{4}+ dfrac{7}{12} ) : dfrac{5}{6} +dfrac{1}{2}
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Bài 2: Thực hiện phép tính một cách hợp lí
f) \(\dfrac{7}{19}\) . \(\dfrac{8}{11}\) + \(\dfrac{3}{11}\) . \(\dfrac{7}{19}\) +\(\dfrac{-12}{19}\)
i) ( \(\dfrac{3}{8}\) + \(\dfrac{-3}{4}\)+ \(\dfrac{7}{12}\) ) : \(\dfrac{5}{6}\) +\(\dfrac{1}{2}\)
f: \(=\dfrac{7}{19}\left(\dfrac{8}{11}+\dfrac{3}{11}\right)-\dfrac{12}{19}=\dfrac{7}{19}-\dfrac{12}{19}=\dfrac{-5}{19}\)
i: \(=\left(\dfrac{9}{24}-\dfrac{18}{24}+\dfrac{14}{24}\right)\cdot\dfrac{6}{5}+\dfrac{1}{2}=\dfrac{5}{24}\cdot\dfrac{6}{5}+\dfrac{1}{2}\)
=1/4+1/2=3/4
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` 7/19 . 8/11 + 3/11 . 7/19 + (-12)/19 `
`= 7/19 . ( 8/11 + 3/11 ) + (-12)/19 `
`= 7/19 . 11/11 + (-12)/19`
`= 7/19 . 1 + (-12)/19 `
`= 7/19 + (-12)/19 `
`= -5/19 `
`( 3/8 + (-3)/4 + 7/12 ) : 5/6 + 1/2`
`= 3/8 + (-3)4 + 7/12 . 6/5 + 1/2`
`= ( 9+(-18) + 14)/24 . 6/5 + 1/2`
`= 5/24 . 6/5 + 1/2`
`= 1/4 + 1/2 `
`= 3/4`
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