Bài 2:
a: \(x-\dfrac{1}{3}=\dfrac{5}{14}\cdot\dfrac{-7}{6}=\dfrac{-35}{84}=\dfrac{-5}{12}\)
nên \(x=-\dfrac{5}{12}+\dfrac{1}{3}=\dfrac{-1}{12}\)
b: \(\Leftrightarrow x\cdot\dfrac{1}{4}=\dfrac{1}{5}-\dfrac{3}{4}=\dfrac{4-15}{20}=\dfrac{-11}{20}\)
=>x=-11/5
c: \(\Leftrightarrow x^2\cdot\dfrac{1}{12}=\dfrac{4}{3}\)
\(\Leftrightarrow x^2=16\)
=>x=4 hoặc x=-4
1.
a) \(\dfrac{-10}{13}+\dfrac{5}{17}-\dfrac{3}{13}+\dfrac{12}{17}-\dfrac{11}{20}\)
\(=\left(\dfrac{-10}{13}-\dfrac{3}{13}\right)+\left(\dfrac{5}{17}+\dfrac{12}{17}\right)-\dfrac{11}{20}\)
\(=-1+1-\dfrac{11}{20}\)
\(=-\dfrac{11}{20}\)
\(b,\dfrac{3}{4}+\dfrac{-5}{6}-\dfrac{11}{-12}\)
\(=\dfrac{9}{12}+\dfrac{-10}{12}-\left(-\dfrac{11}{12}\right)\)
\(=\dfrac{10}{12}=\dfrac{5}{6}\)
\(c,\left(13\dfrac{4}{9}+2\dfrac{1}{9}\right)-3\dfrac{4}{9}\)
\(=\left(\dfrac{121}{9}+\dfrac{19}{9}\right)-\dfrac{31}{9}\)
\(=\dfrac{102}{9}-\dfrac{31}{9}\)
\(=\dfrac{71}{9}\)
\(d.1,25:\dfrac{15}{20}+\left(25\%-\dfrac{5}{6}\right):4\dfrac{2}{3}\)
\(=\dfrac{5}{4}\times\dfrac{20}{15}+\left(\dfrac{1}{4}-\dfrac{5}{6}\right)\times\dfrac{3}{14}\)
\(=\dfrac{5}{3}+\left(-\dfrac{7}{12}\right)\times\dfrac{3}{14}\)
\(=\dfrac{5}{3}+\left(-\dfrac{1}{8}\right)\)
\(=\dfrac{37}{24}\)
