Respostas

2014-08-26T01:42:51-03:00
 \lim_{x\to 3}  \frac{x^2-9}{x^2+9}

substitui x por 3
 \lim_{x \to 3}  \frac{3^2-9}{3^2+9} = \frac{0}{18} =0

2014-08-26T02:08:57-03:00
Lim. X^2-9 x x^2+9
X--3. ------- -------
X^2+9 X^2+9

Lim _____1_______
X--3. 9x^2+9x^2+18

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