Solution 3.3:3f
From Förberedande kurs i matematik 1
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| - | {{  | + | If we write   | 
| - | <  | + | <math>\text{4}</math>  | 
| - | {{  | + | and   | 
| + | <math>\text{16}</math>  | ||
| + | as  | ||
| + | |||
| + | |||
| + | <math>\begin{align}  | ||
| + | & \text{4}=2\centerdot 2=2^{2} \\   | ||
| + | & 16=2\centerdot 8=2\centerdot 2\centerdot 4=2\centerdot 2\centerdot 2\centerdot 2=2^{4} \\   | ||
| + | \end{align}</math>  | ||
| + | |||
| + | |||
| + | we obtain  | ||
| + | |||
| + | |||
| + | <math>\begin{align}  | ||
| + | & \log _{2}4+\log _{2}\frac{1}{16}=\log _{2}2^{2}+\log _{2}\frac{1}{2^{4}} \\   | ||
| + | & =\log _{2}2^{2}+\log _{2}2^{-4}=2\centerdot \log _{2}2+\left( -4 \right)\centerdot \log _{2}2 \\   | ||
| + | & =2\centerdot 1+\left( -4 \right)\centerdot 1=-2 \\   | ||
| + | \end{align}</math>  | ||
Revision as of 14:28, 25 September 2008
If we write \displaystyle \text{4} and \displaystyle \text{16} as
\displaystyle \begin{align}
& \text{4}=2\centerdot 2=2^{2} \\ 
& 16=2\centerdot 8=2\centerdot 2\centerdot 4=2\centerdot 2\centerdot 2\centerdot 2=2^{4} \\ 
\end{align}
we obtain
\displaystyle \begin{align}
& \log _{2}4+\log _{2}\frac{1}{16}=\log _{2}2^{2}+\log _{2}\frac{1}{2^{4}} \\ 
& =\log _{2}2^{2}+\log _{2}2^{-4}=2\centerdot \log _{2}2+\left( -4 \right)\centerdot \log _{2}2 \\ 
& =2\centerdot 1+\left( -4 \right)\centerdot 1=-2 \\ 
\end{align}
