ĐKXĐ: \(x\ne0\)
\(\frac{2x}{42}=\frac{28}{3x}\) \(\Leftrightarrow\) \(\frac{x}{21}=\frac{28}{3x}\)
\(\Rightarrow3x^2=588\)
\(\Leftrightarrow x^2=196\)
\(\Leftrightarrow\left[\begin{matrix}x=14\\x=-14\end{matrix}\right.\)(thỏa mãn ĐKXĐ)
\(\frac{2x}{42}=\frac{28}{2x}\Rightarrow\frac{x}{21}=\frac{14}{x}\)
\(\Rightarrow x^2=21.14\)
\(\Rightarrow x^2=294\)
\(\Rightarrow x=\left[\begin{matrix}7\sqrt{6}\\-7\sqrt{6}\end{matrix}\right.\)
2x.3x = 42.28
6x2 = 6.7.28
x2 =7.28
x2 = 196
x2 = ( \(\pm\) 14 )2
=> x = \(\pm14\)
