Chapter 5 - Exponential and Logarithmic Functions - 5.6 Logarithmic and Exponential Equations - 5.6 Assess Your Understanding - Page 312: 88

$\frac{1}{4}, 4$

Step 1. Rewrite the equation $log_2(x)\ log_2(x)=4 \longrightarrow (log_2x)^2=4 \longrightarrow log_2x=\pm2 \longrightarrow x=2^{\pm2}=\frac{1}{4}, 4$ Step 2. Check, $x=\frac{1}{4}, 4$ fit the original equation.