Question

[Vũ Minh Hằng]

Tìm x:

\(\dfrac{3x}{2.5}+\dfrac{3x}{5.8}+\dfrac{3x}{8.11}+\dfrac{3x}{11.14}=\dfrac{1}{21}\)

giúp mk với

Answer 1

[Nguyễn Huy Tú]

\(\dfrac{3x}{2.5}+\dfrac{3x}{5.8}+\dfrac{3x}{8.11}+\dfrac{3x}{11.14}=\dfrac{1}{21}\)

\(\Rightarrow x\left(\dfrac{3}{2.5}+\dfrac{3}{5.8}+\dfrac{3}{8.11}+\dfrac{3}{11.14}\right)=\dfrac{1}{21}\)

\(\Rightarrow x\left(\dfrac{1}{2}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{8}+\dfrac{1}{8}-\dfrac{1}{11}+\dfrac{1}{11}-\dfrac{1}{14}\right)=\dfrac{1}{21}\)

\(\Rightarrow x\left(\dfrac{1}{2}-\dfrac{1}{14}\right)=\dfrac{1}{21}\)

\(\Rightarrow x.\dfrac{3}{7}=\dfrac{1}{21}\)

\(\Rightarrow x=\dfrac{1}{21}.\dfrac{7}{3}\)

\(\Rightarrow x=\dfrac{1}{9}\)

Vậy \(x=\dfrac{1}{9}\)

Answer 2

[nhím ngọc]

cậu giỏi thật đấy!