Chapter 7 - Exponential and Logarithmic Functions - 7-3 Logarithmic Functions as Inverses - Lesson Check - Page 456: 9

(a) $\text{not a common logarithm}\\$ (b) $\text{common logarithm}\\$ (c) $\text{common logarithm}\\$ (d) $\text{not a common logarithm}\\$

A common logarithm has a base of $10$. Recall: $\log{a} = \log_{10}{a}$ Among the choices, only $\log{64}$ and $\log_{10}{100}$ have $10$ as base. Thus: (a) $\text{not a common logarithm}\\$ (b) $\text{common logarithm}\\$ (c) $\text{common logarithm}\\$ (d) $\text{not a common logarithm}\\$