Math Is Fun Forum

tony123

Member

Registered: 2007-08-03

Posts: 229

find x

Last edited by tony123 (2007-08-04 03:33:21)

Identity

Member

Registered: 2007-04-18

Posts: 934

Re: find x

I'll wager there's no analytic method to solve this... by inspection I have x=2 as one possible solution.

bossk171

Member

Registered: 2007-07-16

Posts: 305

Re: find x

Graphing it shows that -2 is also a value.

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There are 10 types of people in the world, those who understand binary, those who don't, and those who can use induction.

Ricky

Moderator

Registered: 2005-12-04

Posts: 3,791

Re: find x

To prove that these are the only solutions, simple prove that the function is continuous, if x and y are positive with x < y, then f(x) < f(y), and if x and y are negative with x < y, then f(y) < f(x).  This guarantees the existence of at most 2 solutions.

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"In the real world, this would be a problem.  But in mathematics, we can just define a place where this problem doesn't exist.  So we'll go ahead and do that now..."

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: find x

Graphing it shows that -2 is also a value.

Or you could just note that

This would be simpler that plotting graphs.

Last edited by JaneFairfax (2007-12-18 13:02:08)