Answer
The Product Rule of Logarithms shows that the two expressions are the same.
Work Step by Step
Using the Product Rule of Logarithms, which is given by $\log_b (xy)=\log_bx+\log_by,$ the given expression, $ \log387+\log23 ,$ is equivalent \begin{array}{l}\require{cancel} \log(387\times23) .\end{array} Hence, the answers for Exercise 23 and Exercise 19 are the same.