Bài 1:
a) \(\dfrac{4}{5}-\dfrac{7}{6}+\dfrac{-6}{15}=\dfrac{24}{30}-\dfrac{35}{30}+\dfrac{-12}{30}=\dfrac{24-35+-12}{30}=\dfrac{-23}{30}\)
b) \(\dfrac{-5}{9}.\dfrac{7}{13}+\dfrac{6}{13}.\dfrac{-5}{9}+3\dfrac{7}{9}\)
\(=\dfrac{-5}{9}.\left(\dfrac{7}{13}+\dfrac{6}{13}\right)+\dfrac{34}{9}\)
\(=\dfrac{-5}{9}.1+\dfrac{34}{9}\)
\(=\dfrac{-5}{9}+\dfrac{34}{9}\)
\(=\dfrac{29}{9}\)
c) \(6\dfrac{3}{8}-\left(4\dfrac{3}{8}-\dfrac{1}{2}\right)=\dfrac{51}{8}-\dfrac{35}{8}+\dfrac{1}{2}=\left(\dfrac{51}{8}-\dfrac{35}{8}\right)+\dfrac{1}{2}=2+\dfrac{1}{2}=\dfrac{5}{2}\)
d) \(2\dfrac{1}{3}.1,5-\left(\dfrac{11}{10}+50\%\right):\dfrac{4}{15}\)
\(=\dfrac{7}{3}.1,5-\dfrac{8}{5}:\dfrac{4}{15}\)
\(=\dfrac{7}{2}-6\)
\(=\dfrac{-5}{2}=-2,5\)
Bài 2:
a) \(\dfrac{3}{2}+x=\dfrac{-5}{3}\)
\(x=\dfrac{-5}{3}-\dfrac{3}{2}\)
\(x=\dfrac{-19}{6}\)
b) \(5\dfrac{2}{3}-\left(\dfrac{3}{2}+x\right)=4\dfrac{1}{3}\)
\(\dfrac{3}{2}+x=\dfrac{17}{3}-\dfrac{13}{3}\)
\(\dfrac{3}{2}+x=\dfrac{4}{3}\)
\(x=\dfrac{4}{3}-\dfrac{3}{2}\)
\(x=\dfrac{-1}{6}\)
b) \(\left|x-\dfrac{1}{2}\right|+75\%=\dfrac{9}{10}\)
\(\left|x-\dfrac{1}{2}\right|=\dfrac{9}{10}-75\%\)
\(\left|x-\dfrac{1}{2}\right|=\dfrac{3}{20}\)
\(\Rightarrow\left[{}\begin{matrix}x-\dfrac{1}{2}=\dfrac{3}{20}\\x-\dfrac{1}{2}=\dfrac{-3}{20}\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x=\dfrac{13}{20}\\x=\dfrac{7}{20}\end{matrix}\right.\)
các bạn giúp mình nhnh với ạ , cảm ơn các bạn nhiều
