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Cậu tính từng bước là ra thui

\(B=81.\left(\frac{12-\frac{12}{7}-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}:\frac{5+\frac{5}{13}+\frac{5}{169}+\frac{5}{91}}{6+\frac{6}{13}+\frac{6}{169}+\frac{6}{91}}\right).\frac{158158158}{711711711}\)

\(\Leftrightarrow B=81.\left(\frac{12\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}{4\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}:\frac{5\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}{6\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}\right).\frac{158\left(1001001\right)}{711\left(1001001\right)}\)

\(\Leftrightarrow B=81\left(\frac{12}{3}:\frac{5}{6}\right).\frac{158}{711}\)

\(\Leftrightarrow B=81\left(3.\frac{6}{5}\right).\frac{2}{9}\)

\(\Leftrightarrow B=81.\frac{18}{5}.\frac{2}{9}\)

\(\Leftrightarrow B=\frac{324}{5}\)

Hok tốt!!

26 tháng 1 2016

\(B=81.\left[\frac{3\left(12-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}\right)}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}:\frac{5\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}{6\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}\right].\frac{79.2.1001001}{79.9.1001001}\)

\(B=81.\left[3.\frac{6}{5}\right].\frac{2}{9}\)

\(B=\frac{9.9.3.6.2}{5.9}\)

\(B=\frac{9.3.6.2}{5}\)

\(B=\frac{324}{5}\)

Tick cho minh nha Quang Hai Duong tick minh may man ca nam

26 tháng 1 2016

Kakashi_kun linh tinh vừa thôi

24 tháng 12 2018

bạn ơi

3 tháng 3 2020

P/s : nhìn thì khủng thật ! :v

\(B=81.\left[\frac{\left[12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}\right]}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}:\frac{5+\frac{5}{13}+\frac{5}{169}+\frac{5}{91}}{6+\frac{6}{13}+\frac{6}{169}+\frac{6}{91}}\right].\frac{158158158}{711711711}\)

\(B=81.\left[\frac{12.\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}{4.\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}:\frac{5.\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}{6.\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}\right].\frac{158}{711}\)

\(B=81.\left(\frac{3}{1}:\frac{5}{6}\right).\frac{158}{711}\)

\(B=81.\frac{18}{5}.\frac{158}{711}\)

\(B=\frac{1458}{5}.\frac{158}{711}=\frac{324}{5}\)

Vậy  \(B=\frac{324}{5}\)

4 tháng 2 2018

Ta có \(81.\left(\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{3}{85}}:\frac{5+\frac{5}{13}+\frac{5}{169}+\frac{5}{91}}{6+\frac{6}{13}+\frac{6}{169}+\frac{6}{91}}\right)\)

\(=81.\left(\frac{12.\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}{4.\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}:\frac{5.\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}{6.\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}\right)\)

\(=81.\left(\frac{12}{4}:\frac{5}{6}\right)\)

\(=81.\frac{18}{5}\)

\(=291,6\)

4 tháng 2 2018

\(81\left(\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}:\frac{5+\frac{5}{13}+\frac{5}{169}+\frac{5}{91}}{6+\frac{6}{13}+\frac{6}{159}+\frac{6}{91}}\right)\)

\(=81\left(\frac{12\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}{4\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}:\frac{5\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}{6\left(1+\frac{1}{13}+\frac{2}{169}+\frac{1}{91}\right)}\right)\)

\(=81\left(3\div\frac{5}{6}\right)\)

\(=81.\frac{18}{5}\)

\(=\frac{1458}{5}\)

15 tháng 3 2018

\(a)\) \(A=\frac{5\left(2^2.3^2\right)^9.\left(2^2\right)^6-2\left(2^2.3\right)^{14}.3^4}{5.2^{28}.3^{18}-7.2^{29}.3^{18}}\)

\(A=\frac{2^{30}.3^{18}.5-2^{29}.3^{18}}{2^{28}.3^{18}.5-2^{29}.3^{18}.7}\)

\(A=\frac{2^{29}.3^{18}\left(2.5-1\right)}{2^{28}.3^{18}\left(5-2.7\right)}\)

\(A=\frac{2\left(10-1\right)}{5-14}\)

\(A=\frac{2.9}{-9}\)

\(A=-2\)

Vậy \(A=-2\)

\(b)\) \(B=81.\left[\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}:\frac{5+\frac{5}{13}+\frac{5}{169}+\frac{5}{91}}{6+\frac{6}{13}+\frac{6}{169}+\frac{6}{91}}\right].\frac{158158158}{711711711}\)

\(B=81.\left[\frac{12\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}{4\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}:\frac{5\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}{6\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}\right].\frac{158158158}{711711711}\)

\(B=81.\left[\frac{12}{4}:\frac{5}{6}\right].\frac{2}{9}\)

\(B=81.\frac{18}{5}.\frac{2}{9}\)

\(B=\frac{324}{5}\)

Vậy \(B=\frac{324}{5}\)

Chúc bạn học tốt ~ ( mỏi tay qué >_< ) 

28 tháng 9 2017

chịu thôi

19 tháng 3 2019

B=64,8

7 tháng 4 2017

\(A=81.\left[\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}:\frac{5+\frac{5}{13}+\frac{5}{169}+\frac{5}{91}}{6+\frac{6}{13}+\frac{6}{169}+\frac{6}{91}}\right].\frac{158158158}{711711711}\)

\(A=81.\left[\frac{12.\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}{4.\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}:\frac{5.\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}{6.\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}\right].\frac{158}{711}\)

\(A=81.\left(\frac{12}{4}:\frac{5}{6}\right).\frac{2}{9}\)

\(A=81.3.\frac{6}{5}.\frac{2}{9}\)

\(A=\frac{324}{5}\)

Nhớ là: THANKS YOU VERY "MUCH" chứ không phải là  THANKS YOU VERY "MATH"!!!

7 tháng 4 2017

\(A=81.\frac{158158158}{711711711}.\frac{12.\left(\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}{4.\left(\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}:\frac{5.\left(\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}{6.\left(\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}\)

\(=81.\frac{158}{711}.\frac{12}{4}:\frac{5}{6}=\frac{1422}{79}.3.\frac{6}{5}=\frac{1422.3.6}{79.5}=\frac{25596}{395}\)

26 tháng 3 2020

\(B=81\cdot\left(\frac{12-\frac{12}{7}-\frac{12}{289}-\frac{12}{85}}{4-\frac{4}{7}-\frac{4}{289}-\frac{4}{85}}:\frac{5+\frac{5}{13}+\frac{5}{169}+\frac{5}{91}}{6+\frac{5}{13}+\frac{5}{169}+\frac{5}{91}}\right)\cdot\frac{158158158}{711711711}\)

\(B=81\cdot\left(\frac{12\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}{4\left(1-\frac{1}{7}-\frac{1}{289}-\frac{1}{85}\right)}:\frac{5\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)}{5\left(1+\frac{1}{13}+\frac{1}{169}+\frac{1}{91}\right)+1}\right)\cdot\frac{2}{9}\)

\(B=81\cdot\left(\frac{12}{4}:\frac{6470}{7653}\right)\cdot\frac{2}{9}\)

Xem lại đề bài bẹn owii -.-