Question

bài 1: thực hiện phép tính : 

                       \(\left(\frac{41}{75}+\frac{17}{100}\right):\frac{-129}{80}\)

bài 2 : Rút gọn biểu thức M = \(\frac{\frac{1}{4}-\frac{1}{6}-2}{\frac{1}{3}-\frac{1}{4}-2}\)

Answer 1

bài 1:

43/60.(-80/129)

=-4/9

Answer 2

bài 2:

3/12-2/12-24/12

4/12-3/12-24/12

=1/12(3-2-24)

  1/12(4-3-24)

=3-2-24 

  4-3-24

=-23/(-23)=1

Answer 3

\(\left[\frac{41}{75}+\frac{17}{100}\right]:\frac{-129}{80}=\left[\frac{41}{75}+\frac{17}{100}\right]\cdot\frac{-80}{129}\)

\(=\left[\frac{41\cdot4}{300}+\frac{17\cdot3}{300}\right]\cdot\frac{-80}{129}\)

\(=\left[\frac{164}{300}+\frac{51}{300}\right]\cdot\frac{-80}{129}\)

\(=\frac{43}{60}\cdot\frac{-80}{129}=\frac{1}{3}\cdot\frac{-4}{3}=\frac{-4}{9}\)

Bài 2 : \(M=\frac{\frac{1}{4}-\frac{1}{6}-2}{\frac{1}{3}-\frac{1}{4}-2}=\frac{\frac{1\cdot3}{12}-\frac{1\cdot2}{12}-\frac{8\cdot3}{12}}{\frac{1\cdot4}{12}-\frac{1\cdot3}{12}-\frac{8\cdot3}{12}}\)

\(=\frac{\frac{3}{12}-\frac{2}{12}-\frac{24}{12}}{\frac{4}{12}-\frac{3}{12}-\frac{24}{12}}=\frac{\frac{1}{12}\left[3-2-24\right]}{\frac{1}{12}\left[4-3-24\right]}=\frac{3-2-24}{4-3-24}=\frac{-23}{-23}=1\)