Carlos Eugenio Thompson Pinzón

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bio website blog.chlewey.net location Bogotá age 41 member for 5 months seen Feb 13 at 0:37 profile views 284

Human being, or so they say.

Electronics Engineer who has rather worked in Datacom and IT, freelance developer, former IMO contestant who could not solve 1988's 6th problem, and MSc in Mathematics dropout.

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 Feb13 revised parametrization of plane in $\mathbb R^3$ TeXing a little Feb11 comment Interior of the sum of two sets? No. Let $A=\mathbb Q\cap[0,1]$, then $\operatorname{int}(\operatorname{cl}(A))=(0,1)$ while $\operatorname{int}(A)=\emptyset$. Jan20 reviewed Reject suggested edit on Inequality $\frac{1-3ab}{1-2ac}+\frac{1-3bc}{1-2ba}+\frac{1-3ca}{1-2cb}\geq 0$ Dec23 comment I need prove about convexity So, what does the definition of convex function tell you from the identity $x_1 = \mu x+(1-\mu) x_2$ where $\mu\in(0,1)$? (And why we know $\mu\in(0,1)$?) Dec23 comment I need prove about convexity Math.SE is not the place to come to have other people do the homework for you. Do you at least have a definition of convex function? Dec23 revised component of a vector $\mathbf a$ onto vector $\mathbf b$ TeXing a little Dec23 comment Derivative change sign By extremum do you mean a local minimum or maximum? Dec23 revised how to show $\frac{\partial\hat\sigma}{\partial\hat u}\times\frac{\partial\hat\sigma}{\partial\hat v}$ (cross product) TeXing the title Dec23 reviewed Approve suggested edit on how to show $\frac{\partial\hat\sigma}{\partial\hat u}\times\frac{\partial\hat\sigma}{\partial\hat v}$ (cross product) Dec23 comment I need prove about convexity There are several ways @Chapuller, but I would like to see your work first. What have you tried to solve this problem? Dec23 revised determine basis for given vector space TeXing the image Dec23 answered I need prove about convexity Dec23 reviewed Reviewed I need prove about convexity Dec23 revised I need prove about convexity TeXing for formality Dec23 answered Inequality in triangle involving medians Dec23 comment Prove using induction : $n < 3^n$ Write: “R.H.S. $= 3^{p+1}$” and go on. Dec23 comment Prove using induction : $n < 3^n$ Hint: What does $3^n$ means when $n=p+1$? Dec23 revised Prove using induction : $n < 3^n$ TeXing a little Dec23 comment A bijection between (0,5) and (10,20)? Proving that it has inverse (and that inverse is a function, meaning that it is well defined to each point in the domain) is usually enough. Dec23 comment A bijection between (0,5) and (10,20)? Hint: prove that $f(x)=2x+10$ is a bijection.