log 18+log 12=log8−1+log2−1\log\;\frac{1}{8} + \log\;\frac{1}{2} = \log 8^{-1} + \log 2^{-1}log81+log21=log8−1+log2−1
= log2−3+log2−1\log 2^{-3} + \log 2^{-1}log2−3+log2−1
= −3log2−1log2=−4log2-3\log 2 - 1\log 2 = -4\log 2−3log2−1log2=−4log2
