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24 tháng 6

\(\left(2\dfrac{2}{15}\cdot\dfrac{9}{17}\cdot\dfrac{3}{32}\right):\left(-\dfrac{3}{17}\right)\\ =\left(\dfrac{32}{15}\cdot\dfrac{9}{17}\cdot\dfrac{3}{32}\right)\cdot\left(-\dfrac{17}{3}\right)\\ =\dfrac{32}{15}\cdot\dfrac{9}{17}\cdot\dfrac{3}{32}\cdot\dfrac{-17}{3}\\ =\left(\dfrac{32}{15}\cdot\dfrac{3}{32}\right)\cdot\left(\dfrac{9}{17}\cdot\dfrac{-17}{3}\right)\\ =\dfrac{1}{5}\cdot\left(-3\right)=-\dfrac{3}{5}\)

Bài 1:1/\(\left(-\dfrac{25}{13}\right)+\left(-\dfrac{19}{17}\right)+\dfrac{12}{13}+\left(-\dfrac{25}{17}\right)\)                       6/ \(2\dfrac{2}{15}.\dfrac{9}{17}.\dfrac{3}{32}:\left(-\dfrac{3}{17}\right)\)2/\(\dfrac{1}{2}-\left(-\dfrac{1}{3}\right)+\dfrac{1}{23}+\dfrac{1}{6}\)                                           ...
Đọc tiếp

Bài 1:

1/\(\left(-\dfrac{25}{13}\right)+\left(-\dfrac{19}{17}\right)+\dfrac{12}{13}+\left(-\dfrac{25}{17}\right)\)                       6/ \(2\dfrac{2}{15}.\dfrac{9}{17}.\dfrac{3}{32}:\left(-\dfrac{3}{17}\right)\)

2/\(\dfrac{1}{2}-\left(-\dfrac{1}{3}\right)+\dfrac{1}{23}+\dfrac{1}{6}\)                                             7/\(\left(\dfrac{-3}{4}+\dfrac{2}{5}\right):\dfrac{3}{7}+\left(\dfrac{3}{5}+\dfrac{-1}{4}\right):\dfrac{3}{7}\)

3/\(\left(-\dfrac{3}{7}\right).\dfrac{5}{11}+\left(-\dfrac{5}{14}\right).\dfrac{5}{11}\)                                     8/\(\left(-\dfrac{1}{3}\right).\left(-\dfrac{15}{19}\right).\dfrac{38}{45}\)

4/\(\left(-\dfrac{5}{11}\right).\dfrac{7}{15}.\dfrac{11}{-5}.\left(-30\right)\)                                         9/\(\dfrac{1}{2.3}+\dfrac{1}{3.4}+\dfrac{1}{4.5}+......+\dfrac{1}{19.20}\)

5/\(\left(-\dfrac{5}{9}\right).\dfrac{3}{11}+\left(-\dfrac{13}{18}\right).\dfrac{3}{11}\)                                 10/\(\dfrac{1}{9.10}-\dfrac{1}{8.9}-\dfrac{1}{7.8}-......-\dfrac{1}{2.3}-\dfrac{1}{1.2}\)

0
16 tháng 8 2021

Làm chi tiết : Đáp số: \(\dfrac{-3}{40}\)

Ta có: \(D=\left(2\dfrac{2}{15}\cdot\dfrac{9}{17}\cdot\dfrac{3}{32}\right):\left(-\dfrac{3}{17}\right)\)

\(=\dfrac{32}{15}\cdot\dfrac{9}{17}\cdot\dfrac{3}{32}\cdot\dfrac{-17}{3}\)

\(=\dfrac{-9}{15}=-\dfrac{3}{5}\)

24 tháng 8 2023

ai trl tui tick cho

\(=\dfrac{9}{680}:\dfrac{-3}{7}=\dfrac{-21}{680}\)

17 tháng 8 2021

a) \(\dfrac{-5}{9}+\dfrac{3}{5}-\dfrac{3}{9}+\dfrac{-2}{5}\)

=\(\left(\dfrac{-5}{9}-\dfrac{3}{9}\right)+\left(\dfrac{3}{5}+\dfrac{-2}{5}\right)\)

=\(\dfrac{-8}{9}+\dfrac{1}{5}=-\dfrac{31}{45}\)

b) \(\dfrac{5}{17}-\dfrac{9}{15}-\dfrac{2}{17}+\dfrac{-2}{5}\)

=\(\left(\dfrac{5}{17}-\dfrac{2}{17}\right)-\left(\dfrac{9}{15}+\dfrac{2}{5}\right)\)

=\(\dfrac{3}{17}-1=\dfrac{-14}{17}\)

 

17 tháng 8 2021

a) (-5/9) + 3/5 - 3/9 + (-2/5)

= (-5/9) - 3/9 + 3/5 + (-2/5)

= (-2/9) + 1/5

= -1/45

b) 5/17 - 9/15 - 2/17 + (-2/5)

= 5/17 - 2/17 - 9/15 + (-2/5)

= 3/17 - 1/5

= -2/85

Chúc bạn học tốt!! ^^

 

\(\Leftrightarrow-\dfrac{16}{279}< \dfrac{x}{9}< =\dfrac{2}{3}\)

\(\Leftrightarrow\dfrac{x}{9}=0\)

hay x=0

a: =27/45-20/45=7/45

b: \(=\dfrac{3}{5}+\dfrac{30}{40}=\dfrac{3}{5}+\dfrac{3}{4}=\dfrac{12}{20}+\dfrac{15}{20}=\dfrac{27}{20}\)

c: \(=\dfrac{8}{13}\left(\dfrac{7}{2}-\dfrac{5}{2}+1\right)=\dfrac{8}{13}\cdot2=\dfrac{16}{13}\)

d: \(=\dfrac{9}{23}\left(\dfrac{5}{17}-\dfrac{22}{17}\right)+11+\dfrac{9}{23}=11\)

22 tháng 2 2022

a) \(\dfrac{3}{5}+\dfrac{-4}{9}=\dfrac{27}{45}+\dfrac{-20}{45}=\dfrac{7}{45}\)

b) \(\dfrac{3}{5}+\dfrac{2}{5}.\dfrac{15}{8}=1.\dfrac{15}{8}=\dfrac{15}{8}\)

c) \(\dfrac{7}{2}.\dfrac{8}{13}+\dfrac{8}{13}.\dfrac{-5}{2}+\dfrac{8}{13}=\dfrac{8}{13}.\left(\dfrac{7}{2}+\dfrac{-5}{2}\right)=\dfrac{8}{13}.1=\dfrac{8}{13}\)

d) \(\dfrac{-5}{17}.\dfrac{-9}{23}+\dfrac{9}{23}.\dfrac{-22}{17}+11\dfrac{9}{23}=\dfrac{9}{23}.\left(\dfrac{-5}{17}+\dfrac{-22}{17}\right)=\dfrac{-243}{391}\)

24 tháng 10 2017

a) \(D=\left(2\dfrac{2}{15}\times\dfrac{9}{17}\times\dfrac{3}{32}\right)\div\left(-\dfrac{3}{17}\right)\)

\(D=\dfrac{32}{15}\times\dfrac{9}{17}\times\dfrac{3}{32}\times\dfrac{-17}{3}\)

\(D=\dfrac{-3}{5}\)

b) \(\dfrac{1}{2}-\dfrac{1}{3\times7}-\dfrac{1}{7\times11}-\dfrac{1}{11\times15}-\dfrac{1}{15\times19}-\dfrac{1}{19\times23}-\dfrac{1}{23\times27}\)

\(=\dfrac{1}{2}-\left(\dfrac{1}{3\times7}+\dfrac{1}{7\times11}+\dfrac{1}{11\times15}+\dfrac{1}{15\times19}+\dfrac{1}{19\times23}+\dfrac{1}{23\times25}\right)\)

\(=\dfrac{1}{2}-\left[\dfrac{1}{4}\left(\dfrac{4}{3\times7}+\dfrac{4}{7\times11}+\dfrac{4}{11\times15}+\dfrac{4}{15\times19}+\dfrac{4}{19\times23}+\dfrac{4}{23\times27}\right)\right]\)

\(=\dfrac{1}{2}-\left[\dfrac{1}{4}\left(\dfrac{1}{3}-\dfrac{1}{7}+\dfrac{1}{7}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{15}+\dfrac{1}{15}-\dfrac{1}{19}+\dfrac{1}{19}-\dfrac{1}{23}+\dfrac{1}{23}-\dfrac{1}{27}\right)\right]\)

\(=\dfrac{1}{2}-\left[\dfrac{1}{4}\left(\dfrac{1}{3}-\dfrac{1}{27}\right)\right]\)

\(=\dfrac{1}{2}-\left[\dfrac{1}{4}\left(\dfrac{9-1}{27}\right)\right]\)

\(=\dfrac{1}{2}-\dfrac{1}{4}\times\dfrac{8}{27}\)

\(=\dfrac{1}{2}-\dfrac{2}{27}\)

\(=.....\)

Đó đến đây bn tự lm nốt. Câu c bn lm tương tự.

Mình cho bn dạng này, nếu bn chưa biết (để lm câu c)

\(\dfrac{x}{y\left(y+x\right)}=\dfrac{x}{y}-\dfrac{x}{y+x}\)

Chúc bn học tốtbanhbanhbanhbanhbanh

7 tháng 10 2023

Muốn làm những bài toán có chứa hỗn số thì em cần nhớ:

Bước 1: Chuyển các hỗn số có trong phép tính thành phân số.

Bước 2: Thực hiện phép tính theo thứ tự thực hiện phép tính

a, \(\dfrac{8\dfrac{1}{2}}{15:\dfrac{5}{17}}\)

\(\dfrac{\dfrac{17}{2}}{15\times\dfrac{17}{5}}\)

\(\dfrac{\dfrac{17}{2}}{3\times17}\)

\(\dfrac{17}{2}\) x \(\dfrac{1}{3\times17}\)

\(\dfrac{1}{6}\)

 

 

giúp mk vs mn ơi , mai cô giáo ktra mk r

a: \(=\dfrac{8}{9}\cdot\dfrac{9}{4}\cdot\dfrac{12}{19}\cdot\dfrac{19}{24}=\dfrac{1}{2}\cdot2=1\)

b: \(=\dfrac{5}{16}\cdot\dfrac{17}{15}\cdot\dfrac{8}{17}=\dfrac{5}{16}\cdot\dfrac{8}{15}=\dfrac{40}{240}=\dfrac{1}{6}\)

c: \(=\dfrac{4}{13}\left(\dfrac{2}{7}+\dfrac{5}{7}\right)-\dfrac{3}{26}=\dfrac{4}{13}-\dfrac{3}{26}=\dfrac{5}{26}\)

c: \(=\dfrac{3}{4}\left(\dfrac{6}{11}+\dfrac{5}{11}\right)-\dfrac{1}{5}=\dfrac{3}{4}-\dfrac{1}{5}=\dfrac{11}{20}\)

20 tháng 9 2023

\(\dfrac{15-x}{14}=\dfrac{5}{7}\\ \left(15-x\right)\times7=5\times14\\ \left(15-x\right)\times7=70\\ 15-x=70:7\\ 15-x=10\\ x=15-10\\ x=5\)

__

\(\dfrac{x}{9}=\dfrac{17}{3}\\ x\times3=17\times9\\ x\times3=153\\ x=153:3\\ x=51\)

__

\(15-\dfrac{x}{2}=\dfrac{3}{7}\\ \dfrac{x}{2}=15-\dfrac{3}{7}\\ \dfrac{x}{2}=\dfrac{102}{7}\\ x\times7=102\times2\\ x\times7=204\\ x=204:7\\ x=\dfrac{204}{7}\)

20 tháng 9 2023

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