Domain Problem

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September 22nd 2008, 03:22 PM
dm10

Domain Problem

What's the domain of G(t) = ln(t^4-1)?

How did you get the answer, the answer in the book says that it's (-infinity, -1) union (1, infinity) but I don't really understand why.
September 22nd 2008, 03:35 PM
Plato

For $x \in \left[ { - 1,1} \right]\quad \Rightarrow \quad \ln \left( {x^4 - 1} \right) \mbox{ is meaningless!}$
September 22nd 2008, 03:38 PM
dm10

Quote:

Originally Posted by Plato

For $x \in \left[ { - 1,1} \right]\quad \Rightarrow \quad \ln \left( {x^4 - 1} \right) \mbox{ is meaningless!}$

What?
September 22nd 2008, 04:55 PM
Plato

Quote:

Originally Posted by dm10

What?

dn10, you have a very hard road of learning ahead of you if you truly want to understand this material.
You should pay more attention to basic definitions.
Of course, if you could care less then forget it.
September 22nd 2008, 05:39 PM
Krizalid

$t^{4}-1=\left( t^{2}+1 \right)\left( t^{2}-1 \right)>0,$ this last 'cause logarithm is defined for numbers greater than zero. Hence, it remains to solve $t^2-1>0$ which gives the expected answer.

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