Question

em ko bt làm anh chị giải giúp em đc ko

Tìm X

a)X x \(\dfrac{2}{5}\) - \(\dfrac{1}{2}\) x \(\dfrac{3}{5}\) = \(\dfrac{3}{10}\)

b)\(\dfrac{7}{20}\) - \(\dfrac{1}{2}\) : X = \(\dfrac{3}{20}\)

c)\(\dfrac{7}{9}\) : (X - \(\dfrac{4}{9}\)) = \(\dfrac{1}{2}\) 

Answer 1

a) \(x\times\dfrac{2}{5}-\dfrac{1}{2}\times\dfrac{3}{5}=\dfrac{3}{10}\)

\(x\times\dfrac{2}{5}-\dfrac{3}{10}=\dfrac{3}{10}\)

\(x\times\dfrac{2}{5}=\dfrac{3}{10}+\dfrac{3}{10}\)

\(x\times\dfrac{2}{5}=\dfrac{3}{5}\)

\(x=\dfrac{3}{5}:\dfrac{2}{5}\)

\(x=\dfrac{3}{5}\times\dfrac{5}{2}\)

\(x=\dfrac{3}{2}\)

b) \(\dfrac{7}{20}-\dfrac{1}{2}:x=\dfrac{3}{20}\)

\(\dfrac{1}{2}:x=\dfrac{7}{20}-\dfrac{3}{20}\)

\(\dfrac{1}{2}:x=\dfrac{1}{5}\)

\(x=\dfrac{1}{2}:\dfrac{1}{5}\)

\(x=\dfrac{1}{2}\times5\)

\(x=\dfrac{5}{2}\)

Answer 2

c) \(\dfrac{7}{9}:\left(x-\dfrac{4}{9}\right)=\dfrac{1}{2}\)

\(x-\dfrac{4}{9}=\dfrac{7}{9}:\dfrac{1}{2}\)

\(x-\dfrac{4}{9}=\dfrac{7}{9}.2\)

\(x-\dfrac{4}{9}=\dfrac{14}{9}\)

\(x=\dfrac{14}{9}+\dfrac{4}{9}\)

\(x=2\)