Product of 2 Increasing Sequences Not Necessarily Increasing

Easy_as_Pi
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Homework Statement


Give an example to show that it is not necessarily true that the product of two eventually increasing sequences is eventually increasing.


Homework Equations


a sequence is eventually increasing if for N\in natural numbers, a_{n+1} \geqa_{n} for all n>N.


The Attempt at a Solution


So, I know this is merely proof by counterexample. I find one example to show that the product of two eventually increasing sequences is not necessarily eventually increasing. The only catch is that I have no idea where to start. There are infinitely many eventually increasing sequences I could multiply together. I know the end goal is to show that a_{n+1} - a_{n} is decreasing or eventually decreasing for all n.
So, ideally, I'd end up with something like -x^{2} after a_{n+1} - a_{n}. I don't want a specific example which will solve this problem. Some guidance as to where to begin would be greatly appreciated, though!
Thanks!
 
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Try picking an eventually increasing sequence whose values are negative.
 
Sorry that I took an eternity to reply. I was at a study session for linear algebra. Thanks so much, Dick. I think you've helped on every question I've posted here. I really appreciate it. I tripped myself up by only thinking about positive sequences. I took increasing and mistakenly correlated it with positive, too. Immediately after your hint, I thought about -1/n, and then found my solution. This series and sequences course has managed to confuse me more than any previous math class.
 
Prove $$\int\limits_0^{\sqrt2/4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx = \frac{\pi^2}{8}.$$ Let $$I = \int\limits_0^{\sqrt 2 / 4}\frac{1}{\sqrt{x-x^2}}\arcsin\sqrt{\frac{(x-1)\left(x-1+x\sqrt{9-16x}\right)}{1-2x}} \, \mathrm dx. \tag{1}$$ The representation integral of ##\arcsin## is $$\arcsin u = \int\limits_{0}^{1} \frac{\mathrm dt}{\sqrt{1-t^2}}, \qquad 0 \leqslant u \leqslant 1.$$ Plugging identity above into ##(1)## with ##u...
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