
Lois C. answered 04/07/20
BA in secondary math ed with 20+ years of classroom experience
Since a log is just an exponent, when you see the expression logb bn, the entire expression is referring to, or describing, the log ( or exponent) that "b"( i.e. the subscript ) must be raised to in order to produce the final value of bn. So think of it this way: b? = bn. Since the bases are both "b", the unknown log ( or exponent) must be "n".