Chapter 4 - Exponential and Logarithmic Functions - Section 4.6 Logarithmic and Exponential Equations - 4.6 Assess Your Understanding - Page 338: 86

$16$

1. $log_{16}(x)+log_4(x)+log_2(x)=7 \Longrightarrow \frac{log(x)}{4log2}+\frac{log(x)}{2log2}+\frac{log(x)}{log2}=7 \Longrightarrow log(x)+2log(x)+4log(x)=28log2 \Longrightarrow (x)^7=2^{28} \Longrightarrow x=16$ 2. Check, $x=16$ fit.