2log212x−10log4x−3=0
$\Leftrightarrow-2\log_2^2 x - 5\log_2 x - 3 = 0$
Đặt $\log_2 x = t$ ta có $2t^2 + 5t + 3 = 0$
+$t = -1 \Rightarrow \log_2 x = - 1\Rightarrow x = \dfrac{1}{2}$
+$t = -\dfrac{3}{2} \Rightarrow \log_2 x = -\dfrac{3}{2} \Rightarrow x = 2^{-\frac{3}{2}}=\dfrac{1}{\sqrt{x^3}}$