# sizz

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 17h comment How to calculate this multi-integral?Apply Fubini's Theorem. 2d accepted A typo in Spivak's solution? 2d accepted An almost upper bound. Is this a counter example? (SPIVAK) May18 accepted $\sup (A+B) = \sup A + \sup B$ May14 comment Sufficient condition to a function be a diffeomorphismWhat about its inverse? May13 comment $\sup (A+B) = \sup A + \sup B$Sorry for my belated answer. I had to go to the hospital last night. If a number is smaller than every real number, then doesn't that mean the number does not exist? I seriously need a concrete numerical example May11 answered proving that a certain function is not differentiable at $(0,0)$ May11 comment $\sup (A+B) = \sup A + \sup B$From your implication, you have for every z greater than x that is as big as y, then we have $x \geq y$ May11 comment $\sup (A+B) = \sup A + \sup B$Regarding my example we have the following: 5 > 4 and $5 \geq 4$ implies 5 > 5 whichh is a false statement May10 comment When is $\det(A+B)=\det(A)+\det(B)$ for positive definite $A$ and positive semidefinite $B$?The 0 matrix and identity works. Maybe a few more May10 comment $\sup (A+B) = \sup A + \sup B$How do I even know when to use this epsilon trick? It was actually given as a hint, I am not so sure when to even use it May10 reviewed Approve suggested edit on Proving that if $\inf S\notin S$, then it is an accumulation point of $S$ May10 answered Prove that $f$ is continuous at a if and only if $\lim _{h\to0} f (a + h) = f(a)$ May10 comment $\sup (A+B) = \sup A + \sup B$"If every real number bigger than x is at least as big as y..."So if $z = 5$ (say) and $x = 4$, and $y = 5$. Something is wrong May9 comment $\sup (A+B) = \sup A + \sup B$But then what would be the point of defining the equality in this question? May9 comment $\sup (A+B) = \sup A + \sup B$Isn't it meangingless to talk about the supremum if the set isn't bounded in the first place? May9 comment $\sup (A+B) = \sup A + \sup B$I accept the truth of your explanation, but I have no intuition or feeling behind it. The whole $\epsilon$ thing is the one thing that's bugging me May8 comment An almost upper bound. Is this a counter example? (SPIVAK)Coudl you look at my updated question? May8 comment Differentiability of function $f(x,y) = |x|^a + |x-y|$.The way I see it, it appears you have no choice but to do it by brute force. That is we have to compute the derivative from the formal definition. I only worked out one partial derivative and it was quite involved already. Many inequalities May8 revised An almost upper bound. Is this a counter example? (SPIVAK)edited tags