Logarithmac Equations

ghi

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Joined
Dec 26, 2011
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How do you find the domain of f(x)=ln(x2-2x-8)-ln(x2-8x) ?
 
Use the log law \(\displaystyle ln(a)-ln(b)=ln(a/b)\) to write your log as:

\(\displaystyle ln(x^{2}-2x-8)-ln(x^{2}-8x)=ln\left(\frac{x^{2}-2x-8}{x^{2}-8x}\right)=ln\left(\frac{(x-4)(x+2)}{x(x-8)}\right)\)

\(\displaystyle ln(u)\) is defined when \(\displaystyle u > 0\).
 
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