Math Is Fun Forum

tony123

Member

Registered: 2007-08-03

Posts: 230

Any suggestions

but

But I'm unable to verify

Any suggestions?

Last edited by tony123 (2008-10-06 05:19:51)

G_Einstein

Member

Registered: 2008-08-30

Posts: 124

Re: Any suggestions

Do you want to prove that logx+log=log xy   or to prove that logx+logy=log xy with the other log that are above?????

Last edited by G_Einstein (2008-10-06 05:42:39)

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Ricky

Moderator

Registered: 2005-12-04

Posts: 3,791

Re: Any suggestions

Remember that for two series, a_n and b_n, when we multiply them, we do not get:

You go about adding them a funny way because:

Indeed, because of this, I would not prove this identity by Taylor series.  Rather, prove it by establishing the exponential laws, and then come up with the corresponding laws for logarithms.

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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..."

TheDude

Member

Registered: 2007-10-23

Posts: 361

Re: Any suggestions

He's not multiplying the series, he's trying to add them.

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JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: Any suggestions

Kurre

Member

Registered: 2006-07-18

Posts: 280

Re: Any suggestions

Indeed, but the rule logx+logy=logxy holds in that interval too so shouldnt it be possible to prove it anyway?