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13 tháng 7 2019

69/157 - (2 + (3 + (4 + 5-1)-1)-1)-1

= 69/157 - (2 + 21/68)-1

= 69/157 - (157/68)-1

= 69/157 - 68/157

= 1/157

13 tháng 7 2019

69/157-1/[(2+(7+1/5)]=69/157-1/(46/5)=69/157-1/5/46=69/157-46/5=-6877/785

17 tháng 9 2020

\(=\left(-\frac{1}{2}-\frac{1}{9}-\frac{7}{18}\right)+\left(\frac{3}{5}+\frac{2}{7}+\frac{4}{35}\right)+\frac{1}{127}\) 

\(=\left(-\frac{9}{18}-\frac{2}{18}-\frac{7}{18}\right)+\left(\frac{21}{35}+\frac{10}{35}+\frac{4}{35}\right)+\frac{1}{127}\) 

\(=\left(-\frac{18}{18}\right)+\frac{35}{35}+\frac{1}{127}\) 

\(=-1+1+\frac{1}{127}\) 

\(=\frac{1}{127}\)

c)  C = ( 1 - 2 ) + ( 3 - 4 ) + ... + ( 79 - 80 )

     C = ( -1 ) + ( -1 ) + ... + ( -1 )

     C = ( -1 ) x ( 80 - 1 + 1 ) : 2

     C = ( -1 ) x 80 : 2

     C = ( -40 )

4 tháng 7 2017

C=1-2+3-4+...+79-80

=(1-2)+(3-4)+...+(79-80)

=-1+(-1)+...+(-1) (có 80 số hạng bàng -1)

=-1*80

=-80

26 tháng 9 2015

a) A = \(\frac{15}{7}:\left(\frac{1}{15}-\frac{7}{5}\right)-\frac{15}{7}:\left(\frac{17}{15}+\frac{11}{5}\right)=\frac{15}{7}:\frac{-20}{15}-\frac{15}{7}:\frac{50}{15}\)

A = \(\frac{15}{7}.\frac{15}{-20}-\frac{15}{7}.\frac{15}{50}=\frac{15}{7}.\left(\frac{-15}{20}-\frac{15}{50}\right)=\frac{15}{7}.\frac{-105}{100}=-\frac{9}{4}\)

b) B = \(\frac{1}{\left(-\frac{2}{3}\right)^4}.\left(-4\right)^2-1^{2016}-10\frac{1}{3}=\frac{1}{\frac{16}{81}}.16-1-10\frac{1}{3}=\frac{81}{16}.16-1-10\frac{1}{3}\)

B = \(81-1-10-\frac{1}{3}=70-\frac{1}{3}=\frac{209}{3}\)

1 tháng 9 2019

a, Tự chép đề bài ((:

\(=\frac{1}{9}\cdot1+\left(-\frac{1}{243}\right)\cdot\frac{9}{2}\)

\(=\frac{1}{9}-\frac{1}{54}\)

\(=\frac{5}{54}\)

b, 1. \(\left(\frac{2^2\cdot2^3}{4^2\cdot16}\right)^{15}\)

\(=\left(\frac{2^5}{2^4\cdot2^4}\right)^5=\left(\frac{2^5}{2^8}\right)^5=\left(\frac{1}{2^3}\right)^5=\left(\frac{1}{8}\right)^5=\frac{1}{8^5}\)(Để vậy đi :v)

     2. \(\left(\frac{2^6}{16^2}\right)^{10}\)

\(=\left(\frac{2^6}{2^8}\right)^{10}=\left(\frac{1}{2^2}\right)^{10}=\frac{1}{2^{20}}\)

c, \(\frac{2^{15}\cdot9^4}{6^6\cdot8^3}\)

\(=\frac{2^{15}\cdot\left(3^2\right)^4}{\left(2\cdot3\right)^6\cdot\left(2^3\right)^3}=\frac{2^{15}\cdot3^8}{2^6\cdot3^6\cdot2^9}=\frac{2^{15}\cdot3^8}{2^{15}\cdot3^6}=\frac{3^2}{1}=3^2=9\)

17 tháng 9 2020

\(\frac{3}{5}+\frac{3}{11}-\left(\frac{-3}{7}\right)+\frac{2}{97}-\frac{1}{35}-\frac{3}{4}+\left(\frac{-23}{44}\right)\)

\(=\frac{3}{5}+\frac{3}{11}+\frac{3}{7}+\frac{2}{97}-\frac{1}{35}-\frac{3}{4}-\frac{23}{44}\)

\(=\left(\frac{3}{5}+\frac{3}{7}-\frac{1}{35}\right)+\left(\frac{3}{11}-\frac{3}{4}-\frac{23}{44}\right)+\frac{2}{97}\)

\(=\left(\frac{21}{35}+\frac{15}{35}-\frac{1}{35}\right)+\left(\frac{12}{44}-\frac{33}{44}-\frac{23}{44}\right)+\frac{2}{97}\)

\(=\frac{35}{35}+\left(\frac{-44}{44}\right)+\frac{2}{97}=1+\left(-1\right)+\frac{2}{97}=\frac{2}{97}\)

17 tháng 9 2020

\(=\left(\frac{3}{5}+\frac{3}{7}-\frac{1}{35}\right)+\left(\frac{3}{11}-\frac{3}{4}-\frac{23}{44}\right)+\frac{2}{97}\) 

\(=\left(\frac{21}{35}+\frac{15}{35}-\frac{1}{35}\right)+\left(\frac{12}{44}-\frac{33}{44}-\frac{23}{44}\right)+\frac{2}{97}\) 

\(=-1+1+\frac{2}{97}\) 

\(=\frac{2}{97}\)