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16 tháng 9 2021

   ( -3,2 ) . ( -2 ) = 6,4

   13,1 . ( -1,2 ) =  - 15,72

   12,6 : ( -4 ) = - 3,15

   ( -5 ) : ( -2,5 ) = 2

đáp án  6,4        -15,72           -3,15         2    

hok tot nha xin k

\(A=\frac{2,5-4.\left(\frac{5}{2}-1,2\right)+\frac{3}{8}}{4.\left(\frac{5}{2}-1,2\right)-\frac{3}{5}:\frac{2}{5}}-\frac{55}{148}\)

\(A=\frac{\frac{5}{2}-4.\left(\frac{25}{10}-\frac{12}{10}\right)+\frac{3}{8}}{4.\left(\frac{25}{10}-\frac{12}{10}\right)-\frac{3}{5}.\frac{5}{2}}-\frac{55}{148}\)

\(A=\frac{\frac{5}{2}-4.\frac{13}{10}+\frac{3}{8}}{4.\frac{13}{10}-\frac{3}{2}}-\frac{55}{148}\)

\(A=\frac{\frac{5}{2}-\frac{26}{5}+\frac{3}{8}}{\frac{26}{5}-\frac{3}{2}}-\frac{55}{148}\)

\(A=\frac{\frac{100}{40}-\frac{208}{40}+\frac{15}{40}}{\frac{52}{10}-\frac{15}{10}}-\frac{55}{148}\)

\(A=\frac{-\frac{93}{40}}{\frac{37}{10}}-\frac{55}{148}\)

\(A=\frac{93}{148}-\frac{55}{148}\)

\(A=\frac{19}{74}\)

\(B=\frac{2,5-4.\left(\frac{5}{2}-1,2\right)+\frac{3}{8}}{4.\left(\frac{5}{2}-1,2\right)-\frac{3}{5}:\frac{2}{5}}-\frac{55}{148}\)

\(B=\frac{\frac{5}{2}-4.\left(\frac{25}{10}-\frac{12}{10}\right)+\frac{3}{8}}{4.\left(\frac{25}{10}-\frac{12}{10}\right)-\frac{3}{5}.\frac{5}{2}}-\frac{55}{148}\)

\(B=\frac{\frac{5}{2}-4.\frac{13}{10}+\frac{3}{8}}{4.\frac{13}{10}-\frac{3}{2}}-\frac{55}{148}\)

\(B=\frac{\frac{5}{2}-\frac{26}{5}+\frac{3}{8}}{\frac{26}{5}-\frac{3}{2}}-\frac{55}{148}\)

\(B=\frac{\frac{100}{40}-\frac{208}{40}+\frac{15}{40}}{\frac{52}{10}-\frac{15}{10}}-\frac{55}{148}\)

\(B=\frac{-\frac{93}{40}}{\frac{37}{10}}-\frac{55}{148}\)

\(B=\frac{93}{148}-\frac{55}{148}\)

\(B=\frac{19}{74}\)

25 tháng 8 2019

\(B=\frac{2,5-4.\left(\frac{5}{2}-1,2\right)+\frac{3}{8}}{4.\left(\frac{5}{2}-1,2\right)-\frac{3}{5}:\frac{2}{5}}-\frac{55}{148}\)

\(B=\frac{\frac{5}{2}-4.\left(\frac{25}{10}-\frac{12}{10}\right)+\frac{3}{8}}{4.\left(\frac{25}{10}-\frac{12}{10}\right)-\frac{3}{5}.\frac{5}{2}}-\frac{55}{148}\)

\(B=\frac{\frac{5}{2}-4.\frac{13}{10}+\frac{3}{8}}{4.\frac{13}{10}-\frac{3}{2}}-\frac{55}{148}\)

\(B=\frac{\frac{5}{2}-\frac{26}{5}+\frac{3}{8}}{\frac{26}{5}-\frac{3}{2}}-\frac{55}{148}\)

\(B=\frac{\frac{100}{40}-\frac{208}{40}+\frac{15}{40}}{\frac{52}{10}-\frac{15}{10}}-\frac{55}{148}\)

\(B=\frac{-\frac{93}{40}}{\frac{37}{10}}-\frac{55}{148}\)

\(B=\frac{93}{148}-\frac{55}{148}\)

\(B=\frac{19}{74}\)

4 tháng 8 2016

\(0,4.0,5.\left(-2,5\right)+\left(1,2-0,45\right):\frac{3}{4}\)

\(=\frac{2}{5}.\frac{1}{2}.\left(\frac{-5}{2}\right)+\left(\frac{6}{5}-\frac{9}{20}\right):\frac{3}{4}\)

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

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

22 tháng 9 2021

1000+26

16 tháng 7 2018

mở dấu trị tuyệt đối ra rồi tính như bình thường

2 tháng 9 2017

a, \(\left|x+1,2\right|=0,5\)

\(\Leftrightarrow\left[{}\begin{matrix}x+1,2=0,5\\x+1,2=-0,5\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=-0,7\\x=-1,7\end{matrix}\right.\)

Vậy ....

b, \(\left|x-\dfrac{1}{2}\right|+\dfrac{5}{6}=1\dfrac{1}{2}\)

\(\Leftrightarrow\left|x-\dfrac{1}{2}\right|=1\dfrac{1}{2}-\dfrac{5}{6}\)

\(\Leftrightarrow\left|x-\dfrac{1}{2}\right|=\dfrac{2}{3}\)

\(\Leftrightarrow\left[{}\begin{matrix}x-\dfrac{1}{2}=\dfrac{2}{3}\\x-\dfrac{1}{2}=\dfrac{-2}{3}\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{7}{6}\\x=\dfrac{-1}{6}\end{matrix}\right.\)

Vậy .....

c, \(\left|x-\dfrac{1}{2}\right|+\dfrac{4}{5}=\left|-3,2+\dfrac{2}{5}\right|\)

\(\left|x-\dfrac{1}{2}\right|+\dfrac{4}{5}=\left|-2,8\right|\)

\(\left|x-\dfrac{1}{2}\right|+\dfrac{4}{5}=2,8\)

\(\left|x-\dfrac{1}{2}\right|=2,8-\dfrac{4}{5}\)

\(\left|x-\dfrac{1}{2}\right|=2\)

\(\Leftrightarrow\left[{}\begin{matrix}x-\dfrac{1}{2}=2\\x-\dfrac{1}{2}=-2\end{matrix}\right.\)

\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{5}{2}\\x=\dfrac{-8}{5}\end{matrix}\right.\)

Vậy ...

2 tháng 9 2017

bn giúp mk hai bài toán trước nữa đi. Cảm ơn nha!