\(\left(\dfrac{2}{5}-3x\right)^2-\dfrac{1}{5}=\dfrac{1}{25}\\ \Rightarrow\left(\dfrac{2}{5}-3x\right)^2=\dfrac{1}{25}+\dfrac{1}{5}=\dfrac{6}{25}\\ \Rightarrow\dfrac{2}{5}-3x=\pm\dfrac{\sqrt{6}}{5}\\ \Rightarrow3x=\dfrac{2\pm\sqrt{6}}{5}\\ \Rightarrow x=\dfrac{2\pm\sqrt{6}}{15}\)
\(\left(\dfrac{2}{5}-3x\right)^2-\dfrac{1}{5}=\dfrac{1}{25}\)
\(\left(\dfrac{2}{5}-3x\right)^2=\dfrac{1}{25}+\dfrac{1}{5}\)
\(\left(\dfrac{2}{5}-3x\right)^2=\dfrac{6}{25}\)
\(\dfrac{2}{5}-3x=\dfrac{\sqrt{6}}{5}\) hoặc \(\dfrac{2}{5}-3x=-\dfrac{\sqrt{6}}{5}\)
\(3x=\dfrac{2-\sqrt{6}}{5}\) hoặc \(3x=\dfrac{2+\sqrt{6}}{5}\)
\(x=\dfrac{2-\sqrt{6}}{15}\) hoặc \(x=\dfrac{2+\sqrt{6}}{15}\)
