Question

\(4\cdot\left(\dfrac{1}{2}-x\right)-5\cdot\left(x-\dfrac{3}{10}\right)=\dfrac{7}{4}\)

Answer 1

Ta có: \(4.\left(\dfrac{1}{2}-x\right)-5.\left(x-\dfrac{3}{10}\right)=\dfrac{7}{4}\)

\(\Rightarrow4.\dfrac{1}{2}-4x-5x-5.\dfrac{3}{10}=\dfrac{7}{4}\)

\(\Rightarrow2-9x-\dfrac{3}{2}=\dfrac{7}{4}\)

\(\Rightarrow2-\dfrac{3}{2}-9x=\dfrac{7}{4}\)

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

\(\Rightarrow\) \(9x=\dfrac{1}{2}-\dfrac{4}{7}\)\(=\dfrac{7}{14}-\dfrac{8}{14}=\dfrac{-1}{14}\)

\(\Rightarrow x=\dfrac{-1}{14}:9=\dfrac{-1}{14}.\dfrac{1}{9}\)

\(\Rightarrow x=\dfrac{-1}{126}\)

Cách làm là như zậy đó, còn kết quả thì mk chưa chắc lắm, chúc bn học tốt!!!