# 2 Proof Questions

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• Dec 31st 2006, 09:49 AM
ThePerfectHacker
Quote:

Originally Posted by CaptainBlank
Pointing at a diagram does not constitute a proof. You will have the
Bourbaki police after you at this rate.

You do not need to lecture me on not using diagrams. I do not use them for proofs and I agree we cannot use them for proofs. I was making it easier for the user to understand.

However, you can use the fact that any quadradic has a maximum with the main coefficient negative. That is what I was saying.
• Dec 31st 2006, 10:00 AM
CaptainBlack
Quote:

Originally Posted by ThePerfectHacker
You do not need to lecture me on not using diagrams. I do not use them for proofs and I agree we cannot use them for proofs. I was making it easier for the user to understand.

You fail to detect humor in this case.

Quote:

However, you can use the fact that any quadradic has a maximum with the main coefficient negative. That is what I was saying.
And what I am saying is that the student cannot assume that in this case
as it is (almost) what they are being asked to proove.

RonL
• Jan 1st 2007, 11:48 PM
ruprotein
what if i say m and n are both not even because it is the special case of elimination of common factors property.
• Jan 3rd 2007, 05:38 PM
ruprotein
how did u get k<=13 and i got k <= -5
• Jan 3rd 2007, 07:46 PM
CaptainBlack
Quote:

Originally Posted by ruprotein
how did u get k<=13 and i got k <= -5

We are looking for real solutions of:

y^2-6y+(k-4)=0

the discriminant of this is:

d=(-6)^2-4(k-4)=52-4k,

and this has to be >=0,m so:

52-4k>=0

which implies thet:

52>=4k,

13>=k,

or k<=13.

If you have something else tell us how you got what you have so we
can see where we/you have gone down different paths.

RonL

RonL
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