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Topic:
Calculus
Replies:
2
Last Post:
Sep 21, 2004 11:27 AM




Re: Calculus
Posted:
Jul 3, 2000 3:13 PM


On 3 Jul 2000, R. wrote:
> Find: > lim (t+1)^9 * (t^21) > x > 2 > Would you just substitute in the 2 for the t's and figure it out > algebraically? >
Sure, you don't need limits to figure this one out, limits should be used when you can't just plug in the numbers, for example, sinx/x for x>0 or (1+x)^x for x>0. There are some artificially cooked situations when you plug in and get the wrong number, for example, f(x)=1 for x=/=0, f(0)=0, then lim (x>0) f(x) = 1, while f(0)=0. But if you deal with expressions involving the elementary functions, you can plug in and get the limit. It's because the elementary functions are continuous.
Michael

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