中等MATH-EXPL-003
Which expression is equal to log a + log b − log c, for positive a, b and c?
A. log(a + b − c)
B. log(ab / c)✓ 答案
C. log(ab) − c
D. (log a)(log b) / log c
解說
A sum of logs is the log of a product, and a difference of logs is the log of a quotient, so the expression is log(ab/c). Logs do not distribute over addition inside the bracket.