\(0,25:\left(10,3-9,8\right)-\frac{3}{4}\\ b,\left(3\frac{4}{5}-2.x\right).1\frac{1}{3}\\ c,\frac{x}{7}=\frac{6}{-21}\\ d,\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}+\frac{1}{110}+\frac{ }{132}\)cái cuối là 1/132
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tính
a, A=\(\frac{1}{90}-\frac{1}{72}-\frac{1}{56}-\frac{1}{42}-\frac{1}{30}-\frac{1}{20}-\frac{1}{12}-\frac{1}{6}-\frac{1}{2}\)
b, B=\(\left(\frac{1}{4}-1\right)\left(\frac{1}{9}-1\right)...\left(\frac{1}{100}-1\right)\left(\frac{1}{121}-1\right)\)
c,C=\(\frac{3}{1.4}+\frac{5}{4.9}+\frac{7}{9.16}+\frac{9}{16.25}+\frac{11}{25.36}\)
a)
\(A=\left(\frac{1}{9}-\frac{1}{10}\right)-\left(\frac{1}{8}-\frac{1}{9}\right)-....-\left(1-\frac{1}{2}\right)=\frac{1}{9}-\frac{1}{10}-\frac{1}{8}+\frac{1}{9}-....-1+\frac{1}{2}\)
\(A=-\left(\frac{1}{10}+1\right)=-\frac{11}{10}\)
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a)\(A=\frac{1}{90}-\frac{1}{72}-\frac{1}{56}-\frac{1}{42}-\frac{1}{30}-\frac{1}{20}-\frac{1}{12}-\frac{1}{6}-\frac{1}{2}\\ \Rightarrow A=-\frac{1}{2}-\frac{1}{6}-\frac{1}{12}-\frac{1}{20}-\frac{1}{30}-\frac{1}{42}-\frac{1}{56}-\frac{1}{72}-\frac{1}{90}\\ \Rightarrow A=-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}\right)\)Đặt \(B=\frac{1}{2}+\frac{1}{6}+...+\frac{1}{72}+\frac{1}{90}\)
\(\Rightarrow B=\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+...+\frac{1}{8\cdot9}+\frac{1}{9\cdot10}\)
\(\Rightarrow B=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+...+\frac{1}{8}-\frac{1}{9}+\frac{1}{9}-\frac{1}{10}\)
\(\Rightarrow B=1-\frac{1}{10}=\frac{9}{10}\)
Ta có : \(A=-B\)
\(\Rightarrow A=-\frac{9}{10}\)
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a) A=\(\frac{1}{90}-\frac{1}{72}-\frac{1}{56}-\frac{1}{42}-\frac{1}{30}-\frac{1}{20}-\frac{1}{12}-\frac{1}{6}-\frac{1}{2}\)
A=\(-\left(\frac{1}{90}+\frac{1}{72}+\frac{1}{56}+\frac{1}{42}+\frac{1}{30}+\frac{1}{20}+\frac{1}{12}+\frac{1}{6}+\frac{1}{2}\right)\)
A=\(-\left(\frac{1}{9.10}+\frac{1}{8.9}+\frac{1}{7.8}+\frac{1}{6.7}+\frac{1}{5.6}+\frac{1}{4.5}+\frac{1}{3.4}+\frac{1}{2.3}+\frac{1}{1.2}\right)\)
A=-\(\left(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+........+\frac{1}{9}-\frac{1}{10}\right)\)
A=-(\(1-\frac{1}{10}\))
A=-\(\frac{9}{10}\)
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Câu 1. Tính hợp lý giá trị các biểu thức sau :a. A ( 689 - 31 ) - ( 269 - 131 )b. B left(frac{1}{2}+frac{2016}{2017}+frac{2017}{2018}+1right)timesleft(frac{2016}{2017}+frac{2017}{2018}+frac{3}{4}right)-left(frac{1}{2}+frac{2016}{2017}+frac{2017}{2018}right)timesleft(frac{2016}{2017}+frac{2017}{2018}+frac{3}{4}+1right)c. C 1-frac{5}{6}+frac{7}{12}-frac{9}{20}+frac{11}{30}-frac{13}{42}+frac{15}{56}-frac{17}{72}+frac{19}{90}
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Câu 1. Tính hợp lý giá trị các biểu thức sau :
a. A = ( 689 - 31 ) - ( 269 - 131 )
b. B = \(\left(\frac{1}{2}+\frac{2016}{2017}+\frac{2017}{2018}+1\right)\times\left(\frac{2016}{2017}+\frac{2017}{2018}+\frac{3}{4}\right)-\left(\frac{1}{2}+\frac{2016}{2017}+\frac{2017}{2018}\right)\times\left(\frac{2016}{2017}+\frac{2017}{2018}+\frac{3}{4}+1\right)\)c. C = \(1-\frac{5}{6}+\frac{7}{12}-\frac{9}{20}+\frac{11}{30}-\frac{13}{42}+\frac{15}{56}-\frac{17}{72}+\frac{19}{90}\)
C\(\frac{1}{1}-\frac{1}{2.3}+\frac{1}{3.4}-\frac{1}{4.5}+\frac{1}{5.6}\)-\(\frac{1}{6.7}\)+\(\frac{1}{7.8}\)-\(\frac{1}{8.9}+\frac{1}{9.10}\)
c=\(\frac{1}{1}-\frac{1}{10}\)
c=\(\frac{9}{10}\)
còn a và b rễ lắm mình ko thích làm bài rễ đâu bạn cố chờ lời giải khác nhé!
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1 tính
a \(\left(\frac{9}{14}-\frac{9}{21}\right):\left(\frac{4}{5}+\frac{5}{6}\right)\)
b \(\frac{7}{10}-\frac{-3}{4}+\frac{-5}{6}-\frac{1}{5}+\frac{-2}{3}\)
c \(\left(-2\right)^2.\left(\frac{3}{4}-0,25\right):\left(2\frac{1}{4}-1\frac{1}{6}\right)\)
d \(-\frac{1}{7}.\left(9\frac{1}{2}-0,75\right):\frac{2}{7}+0,625:1\frac{2}{3}\)
a) 45/343
b) -1/4
c) 24/13
d) -4
bạn cho mình đi
cậu làm cả các bước cho tớ thầy tớ ko có làm kết quả ko đâu
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a)\(-119\frac{3}{4}.\frac{3}{21}-\frac{13}{21}:4+\frac{6}{42}.116\frac{1}{2}\)
b)\(0,25.\left(-1199\frac{1}{2}\right)-\frac{1}{4}.\left(-2004\frac{1}{3}\right)-\frac{5}{4}\)
c)\(1\frac{3}{4}:\left(\frac{-1}{2}+\frac{2}{3}-\frac{5}{6}\right)-\left(-1,75\right)+25\%:2\)
Tính hợp lý:
Tính hợp lý a, 16frac{3}{31}-left(frac{19}{28}+frac{13}{31}right)b, left(24frac{5}{13}+7frac{9}{46}right)-31frac{5}{13}c, frac{1}{20}+frac{1}{30}+frac{1}{42}+frac{1}{56}+frac{1}{72}+frac{1}{90}+frac{1}{110}d,frac{5^2}{1.6}+frac{5^2}{6.11}+frac{5^2}{11.16}+frac{5^2}{16.21}+frac{5^2}{21.26}+frac{5^2}{26.31}e, 1.2+2.4+3.5+4.6+5.7+.............+98.101f,left(frac{1}{2^2}-1right).left(frac{1}{3}-1right).left(frac{1}{4}-1right).............left(frac{1}{100^2}-1right) nói cách làm nhé ,làm dc 1 câu cũng...
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Tính hợp lý
a, \(16\frac{3}{31}-\left(\frac{19}{28}+\frac{13}{31}\right)\)
b, \(\left(24\frac{5}{13}+7\frac{9}{46}\right)-31\frac{5}{13}\)
c, \(\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}+\frac{1}{110}\)
d,\(\frac{5^2}{1.6}+\frac{5^2}{6.11}+\frac{5^2}{11.16}+\frac{5^2}{16.21}+\frac{5^2}{21.26}+\frac{5^2}{26.31}\)
e, 1.2+2.4+3.5+4.6+5.7+.............+98.101
f,\(\left(\frac{1}{2^2}-1\right).\left(\frac{1}{3}-1\right).\left(\frac{1}{4}-1\right).............\left(\frac{1}{100^2}-1\right)\)
nói cách làm nhé ,làm dc 1 câu cũng được ^-^
a,b you cứ tính bt nhé
c)\(\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}+\frac{1}{110}\)
\(=\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}+\frac{1}{7.8}+\frac{1}{8.9}+\frac{1}{9.10}+\frac{1}{10.11}\)
\(=\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}+\frac{1}{8}-\frac{1}{9}+\frac{1}{9}-\frac{1}{10}+\frac{1}{10}-\frac{1}{11}\)
\(=\frac{1}{4}-\frac{1}{11}\)
\(=\frac{7}{44}\)
d) \(\frac{5^2}{1.6}+\frac{5^2}{6.11}+\frac{5^2}{11.16}+\frac{5^2}{16.21}+\frac{5^2}{21.26}+\frac{5^2}{26.31}\)
\(=5\left(\frac{5}{1.6}+\frac{5}{6.11}+\frac{5}{11.16}+\frac{5}{16.21}+\frac{5}{21.26}+\frac{5}{26.31}\right)\)
\(=5\left(1-\frac{1}{6}+\frac{1}{6}-\frac{1}{11}+\frac{1}{11}-\frac{1}{16}+\frac{1}{16}-\frac{1}{21}+\frac{1}{21}-\frac{1}{26}+\frac{1}{26}-\frac{1}{31}\right)\)
\(=5\left(1-\frac{1}{31}\right)\)
\(=5.\frac{30}{31}\)
\(=\frac{150}{31}\)
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Bài 1: Tính giá trị của biểu thức
a) Afrac{left(2,1-1965right):left(1,2.0,045right)}{0,00325:0,013}-frac{1:0,25}{1,6.0,625}
b) Bleft[frac{left(2,4+1frac{5}{4}right).4,375}{left(frac{2}{3}-frac{1}{6}right)}-frac{left(2,75-1frac{5}{6}right).21}{8frac{3}{20}-0,45}right]:frac{67}{200}
c) Cleft(1+frac{1}{1.3}right).left(1+frac{1}{2.4}right).left(1+frac{1}{3.5}right).....left(1+frac{1}{99.101}right)
Bài 2: Tìm X
a) frac{left(1.2+2.3+3.4+...+98.99right).X}{26950}frac{90}{7}:frac{3}{2}
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Bài 1: Tính giá trị của biểu thức
a) A=\(\frac{\left(2,1-1965\right):\left(1,2.0,045\right)}{0,00325:0,013}-\frac{1:0,25}{1,6.0,625}\)
b) B=\(\left[\frac{\left(2,4+1\frac{5}{4}\right).4,375}{\left(\frac{2}{3}-\frac{1}{6}\right)}-\frac{\left(2,75-1\frac{5}{6}\right).21}{8\frac{3}{20}-0,45}\right]:\frac{67}{200}\)
c) C=\(\left(1+\frac{1}{1.3}\right).\left(1+\frac{1}{2.4}\right).\left(1+\frac{1}{3.5}\right).....\left(1+\frac{1}{99.101}\right)\)
Bài 2: Tìm X
a) \(\frac{\left(1.2+2.3+3.4+...+98.99\right).X}{26950}=\frac{90}{7}:\frac{3}{2}\)
Tính nhanh:
S=\(\frac{3}{4}-0,25-[\frac{7}{3}+(\frac{-9}{2})]-\frac{5}{6}\)
X=\(\frac{1}{90}-\frac{1}{72}-\frac{1}{56}-\frac{1}{42}-\frac{1}{30}-\frac{1}{20}-\frac{1}{12}-\frac{1}{6}-\frac{1}{2}\)
\(S=\frac{3}{4}-0,25-\left[\frac{7}{3}+\left(\frac{-9}{2}\right)\right]-\frac{5}{6}\)
\(S=\frac{3}{4}-\frac{1}{4}-\left[\frac{14}{6}+\left(\frac{-27}{6}\right)\right]-\frac{5}{6}\)
\(S=\frac{1}{2}-\left(\frac{-13}{6}\right)-\frac{5}{6}\)
\(S=\frac{3}{6}-\left(\frac{-13}{6}\right)-\frac{5}{6}\)
\(S=\frac{11}{6}\)
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19 tháng 8 2019 lúc 11:16
e,Afrac{1}{2}+frac{5}{6}+frac{11}{12}+frac{19}{20}+frac{29}{30}+frac{41}{42}left(1-frac{1}{2}right)+left(1-frac{1}{6}right)+left(1-frac{1}{12}right)+left(1-frac{1}{20}right)+left(1-frac{1}{20}right)+left(1-frac{1}{42}right)Rightarrow A1-frac{1}{2}+1-frac{1}{6}+1-frac{1}{12}+1-frac{1}{20}+1-frac{1}{30}+1-frac{1}{42}4-left(frac{1}{2}+frac{1}{6}+frac{1}{12}+frac{1}{20}+frac{1}{30}+frac{1}{42}right)Rightarrow A4-left(frac{1}{1.2}+frac{1}{2.3}+frac{1}{3.4}+frac{1}{4.5}+frac{1}{5.6}+frac{1}{6.7}right)...
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e,\(A=\frac{1}{2}+\frac{5}{6}+\frac{11}{12}+\frac{19}{20}+\frac{29}{30}+\frac{41}{42}=\left(1-\frac{1}{2}\right)+\left(1-\frac{1}{6}\right)+\left(1-\frac{1}{12}\right)+\left(1-\frac{1}{20}\right)+\left(1-\frac{1}{20}\right)+\left(1-\frac{1}{42}\right)\)
\(\Rightarrow A=1-\frac{1}{2}+1-\frac{1}{6}+1-\frac{1}{12}+1-\frac{1}{20}+1-\frac{1}{30}+1-\frac{1}{42}=4-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}\right)\)
\(\Rightarrow A=4-\left(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}+\frac{1}{6.7}\right)=4-\left(\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}+\frac{1}{6}-\frac{1}{7}\right)\)
\(\Rightarrow A=4-\left(\frac{1}{1}-\frac{1}{7}\right)=4-\frac{6}{7}=3\frac{1}{7}\)
BN mún hỏi j vậy, đây k phải câu hỏi, mà có thì phải là toán lớp 6
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a) Tính
\(A=\left(1-\frac{1}{2}\right)\cdot\left(1-\frac{1}{3}\right)\cdot\left(1-\frac{1}{4}\right)\cdot\cdot\cdot\left(1-\frac{1}{2014}\right)\cdot\left(1-\frac{1}{2015}\right)\cdot\left(1-\frac{1}{2016}\right)\)
b) Tìm x:
\(\frac{x-2}{12}+\frac{x-2}{20}+\frac{x-2}{30}+\frac{x-2}{42}+\frac{x-2}{56}+\frac{x-2}{72}=\frac{16}{9}\)
b)
\(x-2.\left(\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}+\frac{1}{6\cdot7}+\frac{1}{7\cdot8}+\frac{1}{8\cdot9}\right)=\frac{16}{9}\)
\(x-2\cdot\left(\frac{1}{3}-\frac{1}{9}\right)=\frac{16}{9}\)
\(x-2=\frac{16}{9}:\left(\frac{1}{3}-\frac{1}{9}\right)\)
\(x-2=8\)
=> x = 10
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a)
\(A=\frac{1}{2}.\frac{2}{3}\cdot\frac{3}{4}\cdot\cdot\cdot\frac{2013}{2014}\cdot\frac{2014}{2015}\cdot\frac{2015}{2016}\)
\(A=\frac{1}{2016}\)
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A = ( 1 - 1/2) . ( 1 - 1/3 ) . (1-1/4) ....(1-1/2015) . (1-1/2016)
A= 1/2 . 2/3 . 3/4...2014/2015 . 2015/2016
A = 1 . 2 . 3 . 4 ... 2014 . 2015/ 2 . 3 . 4 ... 2015 . 2016
A = 1/ 2016
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