Logarithms 102

Algebra Level pending

Solve for x x : log 2 x + log 2 6 = 3 \large \log_{2}x + \log_{2}6 = 3


The answer is 1.33333333333333333333333333333.

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2 solutions

Chew-Seong Cheong
Jul 31, 2020

log 2 x + log 2 6 = 3 log 2 ( 6 x ) = log 2 ( 2 3 ) 6 x = 8 x = 8 6 1.33 \begin{aligned} \log_2 x + \log_2 6 & = 3 \\ \log_2 (6x) & = \log_2 (2^3) \\ 6x & = 8 \\ \implies x & = \frac 86 \approx \boxed{1.33} \end{aligned}

James Watson
Jul 31, 2020

Using logarithm properties, we can combine the 2 logs on the left hand side: log 2 x + log 2 6 = 3 log 2 6 x = 3 \log_{2}x + \log_{2}6 = 3 \Rightarrow \log_{2}6x = 3

Now we can raise everything to a power of 2 and cancel out the log: log 2 6 x = 3 2 log 2 6 x = 2 3 6 x = 8 \log_{2}6x = 3 \Rightarrow 2^{\log_{2}6x} = 2^{3} \Rightarrow 6x = 8

Now using simple rearranging we get: 6 x = 8 x = 4 3 \huge 6x = 8 \Rightarrow x=\boxed{\frac{4}{3}}

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