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7 tháng 8 2016

=\(1+\frac{1}{\frac{3}{2}}+\frac{1}{2}+\frac{1}{4}-1\)

=\(\frac{2}{3}+\frac{1}{2}+\frac{1}{4}\)

=\(\frac{17}{12}\)

20 tháng 6 2018

\(\Leftrightarrow2.\left(\frac{-1}{2}\right).\left(\frac{2}{3}\right)^2-3\left(-\frac{1}{3}\right)^2.\frac{2}{9}:x=3.\left(-\frac{1}{2}\right)-\frac{2}{3}\)

\(\Leftrightarrow-\frac{4}{9}-\frac{1}{3}.\frac{2}{9}:x=-\frac{3}{2}-\frac{2}{3}\)

\(\Leftrightarrow-\frac{4}{6}-\frac{2}{27}:x=-\frac{13}{6}\)

\(\Leftrightarrow\frac{2}{27}:x=-\frac{4}{9}:\frac{-13}{6}\)

\(\Leftrightarrow\frac{2}{27}:x=\frac{31}{18}\)

\(\Leftrightarrow x=\frac{2}{27}:\frac{31}{18}\)

\(\Rightarrow x=\frac{4}{93}\)

Vậy \(x=\frac{4}{93}\)

a) \(\frac{\left(5.2\right)}{3.2}-\frac{1}{2}x+\frac{1}{3}+\frac{1}{5}=\frac{\left(3.2\right)}{5}\)

\(\Leftrightarrow\)\(\frac{1}{2}-\frac{1}{2}x+\frac{8}{15}=\frac{6}{5}\)

\(\Leftrightarrow\)\(\frac{1}{2}-\frac{2}{3}=\frac{1}{2}x\)

\(\Leftrightarrow\)\(-\frac{1}{6}=\frac{1}{2}x\)

\(\Leftrightarrow\)x=-1/3

b) VT= \(\frac{\left(3.5.4.2\right)}{5.2.3}=4\)

\(\Leftrightarrow\left(x-\frac{1}{2}\right):6+4=4:\frac{2}{3}=6\)

\(\Leftrightarrow\left(x-\frac{1}{2}\right):6=2\)

\(\Leftrightarrow x-\frac{1}{2}=12\)

=> x= 12,5

cho 3 k 

\(\left(1-\frac{1}{2^2}\right)\cdot\left(1-\frac{1}{3^2}\right)...\left(1-\frac{1}{10^2}\right)\)

=> \(\left(1-\frac{1}{2}\right)\left(1+\frac{1}{2}\right)\left(1-\frac{1}{3}\right)\left(1+\frac{1}{3}\right)\)\(...\left(1-\frac{1}{10}\right)\cdot\left(1+\frac{1}{10}\right)\)

=> \(\left(1-\frac{1}{2}\right)\cdot\frac{3}{2}\cdot\frac{2}{3}\cdot\frac{4}{3}\cdot\cdot\cdot\frac{9}{10}\cdot\frac{10}{11}\)

=> \(\frac{1}{2}\cdot\frac{3\cdot2\cdot4\cdot\cdot\cdot9\cdot10}{2\cdot3\cdot3\cdot\cdot\cdot10\cdot11}=\frac{1}{2}\cdot\frac{11}{10}=\frac{11}{20}\)

Chúc bn học tốt !

cho mk 3 k nha bn

thanks nhìu

bài này mk ko copy, ko chép mạng, tự nghĩ mất 6 phút . 

có công thức rùi nha !

chúc bn học tốt

1 tháng 9 2019

\(A=\left(3+\frac{1}{2}-\frac{2}{3}\right)-\left(2-\frac{2}{3}+\frac{5}{2}\right)+\left(-5+\frac{5}{2}-\frac{4}{3}\right)\)

\(=3+\frac{1}{2}-\frac{2}{3}-2+\frac{2}{3}-\frac{5}{2}-5+\frac{5}{2}-\frac{4}{3}\)

\(=\left(3-2-5\right)+\left(\frac{1}{2}-\frac{5}{2}+\frac{5}{2}\right)-\left(\frac{2}{3}-\frac{2}{3}+\frac{4}{3}\right)\)

\(=-4-\frac{1}{2}\)

\(=-\frac{9}{2}\)

\(B=\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+...+\frac{1}{72}+\frac{1}{90}\)

\(=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+...+\frac{1}{8.9}-\frac{1}{9.10}\)

\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+...+\frac{1}{8}-\frac{1}{9}+\frac{1}{9}-\frac{1}{10}\)

\(=1-\frac{1}{10}\)

\(=\frac{9}{10}\)

1 tháng 9 2019

\(A=\left(3+\frac{1}{2}-\frac{2}{3}\right)-\left(2-\frac{2}{3}+\frac{5}{2}\right)+\left(-5+\frac{5}{2}-\frac{4}{3}\right)\)

\(A=3+\frac{1}{2}-\frac{2}{3}-2+\frac{2}{3}-\frac{5}{2}-5+\frac{5}{2}-\frac{4}{3}\)

\(A=\left(3-2-5\right)+\left(\frac{1}{2}-\frac{5}{2}+\frac{5}{2}\right)-\left(\frac{2}{3}-\frac{2}{3}+\frac{4}{3}\right)\)

\(A=-4+\frac{1}{2}-\frac{4}{3}\)

\(A=-\frac{29}{6}\)

28 tháng 8 2019

giúp mk với khocroi

21 tháng 7 2018

\(Q=\left(\frac{x^2+1}{x+1}-1\right)\left(\frac{4}{x-1}-\frac{2}{x}\right)=\left(\frac{x^2+1-\left(x+1\right)}{x+1}\right)\left(\frac{4x-2\left(x-1\right)}{x\left(x-1\right)}\right)\)

    \(=\left(\frac{x^2+1-x-1}{x+1}\right)\left(\frac{4x-2x+2}{x\left(x-1\right)}\right)=\left(\frac{x^2-x}{x+1}\right)\left(\frac{2\left(x+1\right)}{x\left(x-1\right)}\right)=\frac{2x\left(x+1\right)\left(x-1\right)}{x\left(x-1\right)\left(x+1\right)}=2\)

Vậy Q = 2

21 tháng 7 2018

Hình như đề là rút gọn thì phải.

Giải

\(Q=\left(\frac{x^2+1}{x+1}-1\right)\left(\frac{4}{x-1}-\frac{2}{x}\right)\)

\(=\left(\frac{x^2}{x}-1\right)\left(\frac{4}{x-1}-\frac{2}{x}\right)=\left(x-1\right)\left(\frac{4}{x-1}-\frac{2}{x}\right)\)

\(=\frac{4\left(x-1\right)}{x-1}-\frac{2\left(x-1\right)}{x}=4-\frac{2x-2}{x}\)