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AP Calculus BC/Unit 1: Limits and Continuity
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Evaluating a Limit by Factoring
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All of the following statements about the limit $$\lim_{x\to3} \frac{x^2-9}{x-3}$$ are true EXCEPT:

A

Cancelling the factor $$x-3$$ in $$\frac{x^2-9}{x-3}$$ is mathematically invalid.

B

After canceling the common factor, the simplified expression becomes $$x+3$$, so the limit as $$x\to3$$ is 6.

C

Factoring $$x^2-9$$ as $$(x-3)*(x+3)$$ reveals a common factor with the denominator.

D

The original function is undefined at $$x=3$$, but the limit exists and equals 6.

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