Question

 Tìm x biết :

                 a) \(0,4:x=x:0,9\)

                 b) \(13\frac{1}{3}:1\frac{1}{3}=26:\left(2x-1\right)\)

Answer 1

a) \(0,4:x=x:0,9\)

\(0,4.\frac{1}{x}=x.\frac{10}{9}\)

\(\frac{1}{x}.\frac{1}{x}=\frac{10}{9}.\frac{10}{4}\)

\(\frac{1}{x^2}=\frac{25}{9}\)

\(\Rightarrow x^2=\frac{1.9}{25}=\frac{9}{25}=\frac{3^2}{5^2}=\left(\frac{3}{5}\right)^2\Rightarrow x=\frac{3}{5}\)

\(\Rightarrow x\in\left\{\frac{3}{5};\frac{-3}{5}\right\}\)

 

b)\(13\frac{1}{3}:1\frac{1}{3}=26:\left(2x-1\right)\)

\(\frac{40}{3}:\frac{4}{3}=26.\frac{1}{2x-1}\)

\(\frac{40}{3}.\frac{3}{4}=26.\frac{1}{2x-1}\)

\(\frac{5}{13}=\frac{1}{2x-1}\)

\(\Rightarrow2x-1=\frac{13.1}{5}=\frac{13}{5}\)