Question 20

[samirbajaj]

Originally Posted by yaser

Hint (from Mr. Hints himself ): Cauchy.

I hope this helps more than it confuses.

OK, you just signed up to explain this after the Final deadline.

If you forget, I will remind you :-)

Thanks.

-Samir

[yaser]

Originally Posted by samirbajaj

OK, you just signed up to explain this after the Final deadline.

The deadline is this coming Tuesday, right?

[fgpancorbo]

Originally Posted by fgpancorbo

, sure, Cauchy like in "Cauchy-Schwarz"? I don't want to sound cocky but I thought about bringing that ammunition myself except that I was unable to identify the inner product but now that I think about it... there is that cross term that looks very much like one... Interesting. Correction; I said earlier that I had the proof, but I still have to work out the details on paper. I just did it in my mind; the actual details are a bit more elaborated but I don't see a problem getting there .

OK, I finally got it . It's a bit more technical that I originally thought. If I am allowed, I think that there is another hint needed, and that's the http://en.wikipedia.org/wiki/Inequal...The_inequality . Professor Yaser, feel free to remove this comment if I am giving too much out. Maybe there is a easier way, but I needed both equalities, http://en.wikipedia.org/wiki/Cauchy%...arz_inequality and http://en.wikipedia.org/wiki/Inequal...The_inequality to prove the option for which I was unable to find a counter example.

[samirbajaj]

Originally Posted by yaser

The deadline is this coming Tuesday, right?

Right.

I can imagine a connection between the hint and the problem, but I couldn't formally pin it down, and instead had to fall back on my intuition (which may be wrong).

I'd love to see a brief explanation related to this after Tuesday.

Thank you.

-Samir

[yaser]

Originally Posted by samirbajaj

I'd love to see a brief explanation related to this after Tuesday.

I am sure an *ANSWER* thread will be forthcoming.