Question 42

Jambmaths question: 

Calculate the logarithm to base 9 of ${{3}^{-4}}\times {{9}^{2}}\times {{(81)}^{-1}}$

Option A: 

2

Option B: 

0

Option C: 

–2

Option D: 

–4

Jamb Maths Solution: 

$\begin{align}  & {{\log }_{9}}[{{3}^{-4}}\times {{9}^{2}}\times {{(81)}^{-1}}]={{\log }_{9}}\left[ \tfrac{1}{81}\times 81\times \tfrac{1}{81} \right] \\ & ={{\log }_{9}}\tfrac{1}{81}={{\log }_{9}}{{81}^{-1}} \\ & ={{\log }_{9}}{{9}^{-2}}=-2{{\log }_{9}}9=-2 \end{align}$

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