How do I find the domain of log10 (x^2 - 4)?

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- Nov 9th 2009, 11:10 PMjzelltDomain of log function
How do I find the domain of log10 (x^2 - 4)?

- Nov 10th 2009, 12:00 AMBacterius
What is the domain is the base 10 logarithm ? It is $\displaystyle 0$. Therefore, the domain of this function is :

$\displaystyle x^2 - 4 \geq 0$

$\displaystyle x^2 \geq 4$

$\displaystyle x \geq 2$ OR $\displaystyle x \leq -2$

Therefore, the domain of this function is $\displaystyle x \leq -2$ and $\displaystyle x \geq 2$ - Nov 10th 2009, 12:26 AMDefunkt
- Nov 10th 2009, 02:39 AMHallsofIvy
Surely you mean "x> 0".

Quote:

Therefore, the domain of this function is :

$\displaystyle x^2 - 4 \geq 0$

$\displaystyle x^2 \geq 4$

$\displaystyle x \geq 2$ OR [tex]x \leq -2[\MATH]

Therefore, the domain of this function is $\displaystyle x \leq -2$ and $\displaystyle x \geq 2$

- Nov 10th 2009, 10:42 AMBacterius
Yes sorry I meant $\displaystyle x \geq 0$.

- Nov 10th 2009, 12:46 PMDefunkt
- Nov 10th 2009, 04:30 PMBacterius
Oh my mistake, sorry. It is indeed $\displaystyle x > 0$ (Speechless)