Suy ra:
\(\left(3a^2-b^2\right)4=\left(a^2+b^2\right)3\)
=> \(12a^2-4b^2=3a^2+3b^2\)
=> \(12a^2-3a^2=3b^2+4b^2\)
=> \(9a^2=7b^2=>\frac{a^2}{b^2}=\left(\frac{a}{b}\right)^2=\frac{7}{9}=>\frac{a}{b}=\sqrt{\frac{7}{9}}\)
Vay: \(\frac{a}{b}=\sqrt{\frac{7}{9}}\)