Thread: limits - please help
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Old September 20th, 2007, 07:36 AM
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Quote:
Originally Posted by sade View Post
Find the limits using first principle:
1. lim (3x-1)5
x® -1
There are no restrictions on the domain of (3x - 1)5 = 15x - 5, so just plug in x = -1.

Quote:
Originally Posted by sade View Post
2. lim Öx-2
x®4 x-4
Is this
\lim_{x \to 4}\frac{\sqrt{x} - 2}{x - 4}

If so, then note that x - 4 = (\sqrt{x} + 2)(\sqrt{x} - 2). Then
\lim_{x \to 4}\frac{\sqrt{x} - 2}{x - 4} = \lim_{x \to 4}\frac{\sqrt{x} - 2}{(\sqrt{x} + 2)(\sqrt{x} - 2)} = \lim_{x \to 4}\frac{1}{\sqrt{x} + 2}.

You take it from here.

-Dan
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