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Re: What's wrong with this assuming?

• To: mathgroup at smc.vnet.net
• Subject: [mg111113] Re: What's wrong with this assuming?
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Tue, 20 Jul 2010 07:55:43 -0400 (EDT)
• Reply-to: hanlonr at cox.net

Use the assumption directly in Simplify or FullSimplify

Simplify[(x^2 + x)^2 + h, x^2 + x == h]

h (h+1)

FullSimplify[(x^2 + x)^2 + h, x^2 + x == h]

h (h+1)

Or put Simplify or FullSimplify within the scope of the Assuming construct

Assuming[x^2 + x == h, Simplify[(x^2 + x)^2 + h]]

h (h+1)

Assuming[x^2 + x == h, FullSimplify[(x^2 + x)^2 + h]]

h (h+1)


Bob Hanlon

---- Sam Takoy <sam.takoy at yahoo.com> wrote: 

=============
Hi,


I have a situation where I have to simplify an expression that contains 
x and h, but x is given implicitly by h, so I can't explicitly eliminate 
it. So here's a simpler example that I'm trying and it does nothing:

Assuming[x^2 + x == h, (x^2 + x)^2+h] // FullSimplify

Is there a way to make this work?

Thanks!


--

Bob Hanlon