tính : (\(\dfrac{1}{68}\) + \(\dfrac{1}{968}\) - \(\dfrac{1}{1968}\) )( \(\dfrac{1}{23}\) - \(\dfrac{1}{6}\) - \(\dfrac{1}{6}\))
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thực hiện phép tính
\(l.\dfrac{\dfrac{1}{3}+\dfrac{1}{7}-\dfrac{1}{23}}{\dfrac{2}{3}+\dfrac{2}{7}-\dfrac{2}{23}}\times\dfrac{\dfrac{1}{3}-0.25-0.2}{1\dfrac{1}{6}-0.875-0.7}\)
\(\dfrac{\dfrac{1}{3}+\dfrac{1}{7}-\dfrac{1}{23}}{\dfrac{2}{3}+\dfrac{2}{7}-\dfrac{2}{23}}\times\dfrac{\dfrac{1}{3}-0,25-0,2}{1\dfrac{1}{6}-0,875-0,7}\)
\(=\dfrac{\dfrac{1}{3}+\dfrac{1}{7}-\dfrac{1}{23}}{\dfrac{1}{3}+\dfrac{1}{3}+\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{23}-\dfrac{1}{23}}\times\dfrac{\dfrac{1}{3}-\dfrac{1}{4}-\dfrac{1}{5}}{\dfrac{7}{6}-\dfrac{7}{8}-\dfrac{7}{10}}\)
\(=\dfrac{\dfrac{1}{3} +\dfrac{1}{7}-\dfrac{1}{23}}{\dfrac{1}{3}\times2+\dfrac{1}{7}\times2-\dfrac{1}{23}\times2}\times\dfrac{\dfrac{2}{6}-\dfrac{2}{8}-\dfrac{2}{10}}{7\times\left(\dfrac{1}{6}-\dfrac{1}{8}-\dfrac{1}{10}\right)}\)
\(=\dfrac{\dfrac{1}{3}+\dfrac{1}{7}-\dfrac{1}{23}}{2\times\left(\dfrac{1}{3}+\dfrac{1}{7}-\dfrac{1}{23}\right)}\times\dfrac{2\times\left(\dfrac{1}{6}-\dfrac{1}{8}-\dfrac{1}{10}\right)}{7\times\left(\dfrac{1}{6}-\dfrac{1}{8}-\dfrac{1}{10}\right)}\)
\(=\dfrac{1}{2}\times\dfrac{2}{7}\)
\(=\dfrac{1}{7}\)
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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) 2.dfrac{3}{7}+left(dfrac{2}{9}-1dfrac{3}{7}right)-dfrac{5}{3}:dfrac{1}{9}
b) dfrac{-11}{23}.dfrac{6}{7}+dfrac{8}{7}.dfrac{-11}{23}-dfrac{1}{23}
c) left(dfrac{377}{-231}-dfrac{123}{89}+dfrac{34}{791}right).left(dfrac{1}{6}-dfrac{1}{8}-dfrac{1}{24}right)
d) 19dfrac{5}{8}:dfrac{7}{12}-15dfrac{1}{4}:dfrac{7}{12}
e) dfrac{2}{5}.dfrac{1}{3}-dfrac{2}{15}:dfrac{1}{5}+dfrac{3}{5}.dfrac{1}{3}
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Tính nhanh:
a) \(2.\dfrac{3}{7}+\left(\dfrac{2}{9}-1\dfrac{3}{7}\right)-\dfrac{5}{3}:\dfrac{1}{9}\)
b) \(\dfrac{-11}{23}.\dfrac{6}{7}+\dfrac{8}{7}.\dfrac{-11}{23}-\dfrac{1}{23}\)
c) \(\left(\dfrac{377}{-231}-\dfrac{123}{89}+\dfrac{34}{791}\right).\left(\dfrac{1}{6}-\dfrac{1}{8}-\dfrac{1}{24}\right)\)
d) \(19\dfrac{5}{8}:\dfrac{7}{12}-15\dfrac{1}{4}:\dfrac{7}{12}\)
e) \(\dfrac{2}{5}.\dfrac{1}{3}-\dfrac{2}{15}:\dfrac{1}{5}+\dfrac{3}{5}.\dfrac{1}{3}\)
Bài 1: Tínha) dfrac{9}{5}+dfrac{2}{5} x dfrac{4}{6} b) dfrac{3}{8} x 2 - dfrac{6}{7} x dfrac{1}{3}Bài 2: Tính bằng cách thuận tiện nhất:a) dfrac{11}{23}+dfrac{2}{23}+dfrac{9}{23}+dfrac{18}{23} b)dfrac{25}{12}+dfrac{17}{6}-dfrac{15}{36}-dfrac{15}{6}Bài 3: Một hình chữ nhật có chiều rộng là dfrac{3}{5} m và bằng một nửa chiều dài. Tính diện tích hình chữ nhật đó.
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Bài 1: Tính
a) \(\dfrac{9}{5}+\dfrac{2}{5}\) x \(\dfrac{4}{6}\) b) \(\dfrac{3}{8}\) x 2 - \(\dfrac{6}{7}\) x \(\dfrac{1}{3}\)
Bài 2: Tính bằng cách thuận tiện nhất:
a) \(\dfrac{11}{23}+\dfrac{2}{23}+\dfrac{9}{23}+\dfrac{18}{23}\) b)\(\dfrac{25}{12}+\dfrac{17}{6}-\dfrac{15}{36}-\dfrac{15}{6}\)
Bài 3: Một hình chữ nhật có chiều rộng là \(\dfrac{3}{5}\) m và bằng một nửa chiều dài. Tính diện tích hình chữ nhật đó.
\(\dfrac{\dfrac{1}{6}-\dfrac{1}{39}+\dfrac{1}{51}}{\dfrac{1}{8}-\dfrac{1}{52}+\dfrac{1}{68}}\)
\(\dfrac{\dfrac{1}{6}-\dfrac{1}{39}+\dfrac{1}{51}}{\dfrac{1}{8}-\dfrac{1}{52}+\dfrac{1}{68}}\)
\(\dfrac{11}{\dfrac{78}{\dfrac{11}{104}+\dfrac{1}{68}}}+\dfrac{1}{51}\)
\(\dfrac{71}{\dfrac{442}{\dfrac{213}{1768}}}\)\(\Rightarrow\dfrac{4}{3}\)
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5dfrac{5}{27}+dfrac{7}{23}-0,5.dfrac{5}{27}+dfrac{16}{23}
45dfrac{1}{6}:left(dfrac{-4}{5}right)-35dfrac{1}{6}:left(dfrac{-4}{5}right)
25.left(dfrac{-1}{5}right)^3+dfrac{1}{5}-2.left(dfrac{-1}{2}right)^2-dfrac{1}{2}
left(3,1-2,5right)-left(-2,5-3,1right)
dfrac{3}{8}.dfrac{7}{5}-dfrac{7}{5}.dfrac{1}{8}+dfrac{13}{20}
CẦN GẤP NGAY VÀ LUÔN :)))))
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\(5\dfrac{5}{27}+\dfrac{7}{23}-0,5.\dfrac{5}{27}+\dfrac{16}{23}=\)
\(45\dfrac{1}{6}:\left(\dfrac{-4}{5}\right)-35\dfrac{1}{6}:\left(\dfrac{-4}{5}\right)=\)
\(25.\left(\dfrac{-1}{5}\right)^3+\dfrac{1}{5}-2.\left(\dfrac{-1}{2}\right)^2-\dfrac{1}{2}=\)
\(\left(3,1-2,5\right)-\left(-2,5-3,1\right)=\)
\(\dfrac{3}{8}.\dfrac{7}{5}-\dfrac{7}{5}.\dfrac{1}{8}+\dfrac{13}{20}=\)
CẦN GẤP NGAY VÀ LUÔN :)))))
Tính giá trị của các biểu thức sau 1) A1+2+2^2+...+2^{2015} 2) Bleft(dfrac{1}{4}-1right)cdotleft(dfrac{1}{9}-1right)cdotleft(dfrac{1}{16}-1right)cdotcdotcdotcdotcdotleft(dfrac{1}{400}-1right) 3) Cleft(dfrac{1}{4cdot9}+dfrac{1}{9cdot14}+dfrac{1}{14cdot19}+...+dfrac{1}{44cdot49}right)cdotdfrac{1-3-5-7-...-49}{89} 4) Ddfrac{2^{12}cdot3^5-4^6cdot9^2}{left(2^2cdot3right)^6+8^4cdot3^5}-dfrac{5^{10}cdot7^3-25^5cdot49^2}{left(125cdot7right)^3+5^9cdot14^3} 5) Edfrac{dfrac{1}{2003}+dfrac{1}{2004}-dfrac{1}...
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Tính giá trị của các biểu thức sau 1) \(A=1+2+2^2+...+2^{2015}\) 2) \(B=\left(\dfrac{1}{4}-1\right)\cdot\left(\dfrac{1}{9}-1\right)\cdot\left(\dfrac{1}{16}-1\right)\cdot\cdot\cdot\cdot\cdot\left(\dfrac{1}{400}-1\right)\) 3) \(C=\left(\dfrac{1}{4\cdot9}+\dfrac{1}{9\cdot14}+\dfrac{1}{14\cdot19}+...+\dfrac{1}{44\cdot49}\right)\cdot\dfrac{1-3-5-7-...-49}{89}\) 4) \(D=\dfrac{2^{12}\cdot3^5-4^6\cdot9^2}{\left(2^2\cdot3\right)^6+8^4\cdot3^5}-\dfrac{5^{10}\cdot7^3-25^5\cdot49^2}{\left(125\cdot7\right)^3+5^9\cdot14^3}\) 5) \(E=\dfrac{\dfrac{1}{2003}+\dfrac{1}{2004}-\dfrac{1}{2005}}{\dfrac{5}{2003}+\dfrac{5}{2004}-\dfrac{5}{2005}}-\dfrac{\dfrac{2}{2002}+\dfrac{2}{2003}-\dfrac{2}{2004}}{\dfrac{3}{2002}+\dfrac{3}{2003}-\dfrac{3}{2004}}\) 6) Cho 13+23+...+103=3025 Tính S= 23+43+63+...+203
Bài 1: Thực hiện phép tính:
a) A = [6.(\(\dfrac{1}{3}\))3- 3 (-\(\dfrac{1}{3}\))+ 1 ] : (-\(\dfrac{1}{3}\)-1)
b) B = \(\dfrac{\dfrac{1}{39}-\dfrac{1}{6}-\dfrac{1}{51}}{\dfrac{1}{8}-\dfrac{1}{52}+\dfrac{1}{68}}:5\dfrac{1}{6}\)
a: \(A=\left[6\cdot\dfrac{1}{27}+3\cdot\dfrac{1}{3}+1\right]:\dfrac{-4}{3}\)
\(=\left(\dfrac{2}{9}+2\right)\cdot\dfrac{-3}{4}\)
\(=\dfrac{20}{9}\cdot\dfrac{-3}{4}=\dfrac{-60}{36}=\dfrac{-5}{3}\)
b: \(B=\dfrac{\dfrac{1}{3}\left(\dfrac{1}{13}-\dfrac{1}{2}-\dfrac{1}{17}\right)}{-\dfrac{1}{4}\left(\dfrac{1}{13}-\dfrac{1}{2}-\dfrac{1}{17}\right)}:\dfrac{11}{6}\)
\(=\dfrac{-1}{3}:\dfrac{1}{4}\cdot\dfrac{6}{11}=\dfrac{-4}{3}\cdot\dfrac{6}{11}=\dfrac{-24}{33}=\dfrac{-8}{11}\)
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a)dfrac{-3}{7}+dfrac{15}{26}-left(dfrac{2}{13}-dfrac{3}{7}right)b)2.dfrac{3}{7}+left(dfrac{2}{9}-1dfrac{3}{7}right)-dfrac{5}{3}:dfrac{1}{9}c)dfrac{-11}{23}.dfrac{6}{7}+dfrac{8}{7}.dfrac{-11}{23}-dfrac{1}{23}d)left(dfrac{377}{-231}-dfrac{123}{89}+dfrac{34}{791}right).left(dfrac{1}{6}-dfrac{1}{8}-dfrac{1}{24}right) nhanh lên giúp mình vs
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a)\(\dfrac{-3}{7}+\dfrac{15}{26}-\left(\dfrac{2}{13}-\dfrac{3}{7}\right)\)
b)\(2.\dfrac{3}{7}+\left(\dfrac{2}{9}-1\dfrac{3}{7}\right)-\dfrac{5}{3}:\dfrac{1}{9}\)
c)\(\dfrac{-11}{23}.\dfrac{6}{7}+\dfrac{8}{7}.\dfrac{-11}{23}-\dfrac{1}{23}\)
d)\(\left(\dfrac{377}{-231}-\dfrac{123}{89}+\dfrac{34}{791}\right).\left(\dfrac{1}{6}-\dfrac{1}{8}-\dfrac{1}{24}\right)\)
nhanh lên giúp mình vs
a) Ta có: \(\dfrac{-3}{7}+\dfrac{15}{26}-\left(\dfrac{2}{13}-\dfrac{3}{7}\right)\)
\(=\dfrac{-3}{7}+\dfrac{15}{26}-\dfrac{2}{13}+\dfrac{3}{7}\)
\(=\dfrac{15}{26}-\dfrac{4}{26}\)
\(=\dfrac{11}{26}\)
b) Ta có: \(2\cdot\dfrac{3}{7}+\left(\dfrac{2}{9}-1\dfrac{3}{7}\right)-\dfrac{5}{3}:\dfrac{1}{9}\)
\(=\dfrac{6}{7}+\dfrac{2}{9}-\dfrac{10}{7}-\dfrac{5}{3}\cdot9\)
\(=\dfrac{-4}{7}+\dfrac{2}{9}-15\)
\(=\dfrac{-36}{63}+\dfrac{14}{63}-\dfrac{945}{63}\)
\(=\dfrac{-967}{63}\)
c) Ta có: \(\dfrac{-11}{23}\cdot\dfrac{6}{7}+\dfrac{8}{7}\cdot\dfrac{-11}{23}-\dfrac{1}{23}\)
\(=\dfrac{-11}{23}\cdot\left(\dfrac{6}{7}+\dfrac{8}{7}\right)-\dfrac{1}{23}\)
\(=\dfrac{-11}{23}\cdot2-\dfrac{1}{23}\)
\(=-1\)
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d) Ta có: \(\left(\dfrac{377}{-231}-\dfrac{123}{89}+\dfrac{34}{791}\right)\cdot\left(\dfrac{1}{6}-\dfrac{1}{8}-\dfrac{1}{24}\right)\)
\(=\left(\dfrac{-377}{231}-\dfrac{123}{89}+\dfrac{34}{791}\right)\cdot\left(\dfrac{4}{24}-\dfrac{3}{24}-\dfrac{1}{24}\right)\)
\(=\left(\dfrac{-377}{231}-\dfrac{123}{89}+\dfrac{34}{791}\right)\cdot0\)
=0
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