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Topic: [ap-calculus] Need help with this log problem
Replies: 1   Last Post: May 25, 2012 4:01 AM

 Jeff Stuart Posts: 1,086 Registered: 12/6/04
Re: [ap-calculus] Need help with this log problem
Posted: May 25, 2012 4:01 AM

Hello Jaime:

First, because of the logs, we must have both x+1 and x-1 positive. Also,
I am reading log2(stuff) as log (base 2) of stuff. Second, 8 = log2(2^8),
so we have

log2(x+1) = log2( 2^8 / (x-1) )

so

x+1 = 2^8 / (x-1)

(x+1)*(x-1) = 2^8

x^2 -1 = 256

x^2 = 257

x = +sqrt(257) since we cannot have x-1 negative.

--
Professor Jeff Stuart, Chair
Department of Mathematics
Pacific Lutheran University
jeffrey.stuart@plu.edu
(253) 535 7403

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Course related websites:
http://apcentral.collegeboard.com/calculusab
http://apcentral.collegeboard.com/calculusbc
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