Suppose that \(\ln A = 3\) and \(\ln B = 4\) . Find the exact value of \(\ln ( A ^ { 2 } \cdot B )\) .
Question
Answer
10
\(\ln ( A ^ { 2 } B ) = 2 \ln ( A ) + \ln ( B )\)
\(\ln ( A ^ { 2 } B )\)
Apply log rule: \( \log _ { c } ( a b ) = \log _ { c } ( a ) + \log _ { c } ( b )\)
\(\ln ( A ^ { 2 } B ) = \ln ( A ^ { 2 } ) + \ln ( B )\)
\(= \ln ( A ^ { 2 } ) + \ln ( B )\)
Apply log rule: \( \log _ { a } ( x ^ { b } ) = b - \log _ { a } ( x )\)
\(\ln ( A ^ { 2 } ) = 2 \ln ( A )\)
\(= 2 \ln ( A ) + \ln ( B )\)