Question

Bài 1: Tìm x, biết a) \(-\frac{3}{4}-\left(x+\frac{1}{2}\right)=1\frac{2}{3}\) b) \(3,15:0,4=2,1x:1,68\)

Answer 1

Bài 1: Tìm x

a) Ta có: \(-\frac{3}{4}-\left(x+\frac{1}{2}\right)=1\frac{2}{3}\)

\(\Leftrightarrow\frac{-3}{4}-x-\frac{1}{2}=\frac{5}{3}\)

\(\Leftrightarrow-x-\frac{5}{4}=\frac{5}{3}\)

\(\Leftrightarrow-x=\frac{5}{3}+\frac{5}{4}=\frac{35}{12}\)

hay \(x=-\frac{35}{12}\)

Vậy: \(x=-\frac{35}{12}\)

b) Ta có: \(3.15:0.4=2.1x:1.68\)

\(\Leftrightarrow\frac{63}{20}:\frac{2}{5}=\frac{21}{10}x:\frac{168}{100}\)

\(\Leftrightarrow x\cdot\frac{21}{10}:\frac{168}{100}=\frac{63}{8}\)

\(\Leftrightarrow x\cdot\frac{21}{10}=\frac{63}{8}\cdot\frac{168}{100}=\frac{1323}{100}\)

\(\Leftrightarrow x=\frac{1323}{100}:\frac{21}{10}=\frac{63}{10}\)

Vậy: \(x=\frac{63}{10}\)