Problems from Rational functions

Development:

1. We have a rational function, and therefore we must look at the points where the denominator is zero: $$x+3=0\Rightarrow x=-3$$ Therefore $Dom(f)=\mathbb{R}-\{-3\}$.

2. As in the previous case, we look at the points where the denominator is zero: $$x^2-9=0\Rightarrow x^2=9\Rightarrow x=\pm 3$$ Therefore $Dom(f)=\mathbb{R}-\{-3,3\}$.

3. This case is just as the previous ones but obviously the denominator is zero at $0$. Therefore, $Dom(f)=\mathbb{R}-\{0\}$.

Solution:

1. $Dom(f)=\mathbb{R}-\{-3\}$
2. $Dom(f)=\mathbb{R}-\{-3,3\}$
3. $Dom(f)=\mathbb{R}-\{0\}$

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