${{\log }_{x}}2- {{ \log }_{4}}x\frac{7}{6}=0$ (b)

Phương trình: ${{\log }_{x}}2-{{\log }_{4}}x+\frac{7}{6}=0.$ Điều kiện: $0

Đặt $t={{\log }_{2}}x$

(b)$\Leftrightarrow \frac{1}{{{\log }_{2}}x}-\frac{1}{2}{{\log }_{2}}x+\frac{7}{6}=0\Leftrightarrow \frac{1}{t}=\frac{t}{2}+\frac{7}{6}=0\Leftrightarrow 3{{t}^{2}}-7t-6=0\Leftrightarrow \left[ \begin{align}  & t=3 \\  & t=-\frac{2}{3} \\ \end{align} \right.$

• $t={{\log }_{2}}x=3\Leftrightarrow x={{2}^{3}}=8$


• $t={{\log }_{2}}x=-\frac{2}{3}\Leftrightarrow x={{2}^{\frac{2}{3}=}}=\frac{1}{\sqrt[3]{4}}$