# wangdw

Beijing, China

Windows 7 for entertainment. Ubuntu for the rest.

 Sep 7 awarded Teacher Sep 7 answered Why do 1000 rpm and 10 rpm DC motors cost the same? Aug 19 answered What is an effective distribution of grayscale sensors on robot May 7 comment How to play Mp3 files using Rhythmbox?Also, you could just open a terminal and type sudo apt-get install ubuntu-restricted-extras. May 6 comment Find $s$ and $t$ with substitution?$5\sqrt s-\sqrt{4t}=10\rightarrow5\sqrt s=10+\sqrt{2s+7}$. Square both sides up: $23s-107=20\sqrt{2s+7}$; then square again. May 6 comment how to install ubuntu 32bit with wubiShortcut? You can directly download the 32bit image from the official website of Ubuntu. May 6 comment I cannot use hibernate/sleep in Ubuntu 12.04There exist multiple duplicates of this question. Please be more specific! May 6 awarded Supporter May 6 awarded Commentator May 6 comment Probability of BirthdaysIntuitively, $$P=\frac1{7^3}\left[\binom71\binom32\binom61+\binom71\right]=0.388$$ May 6 awarded Commentator May 6 comment Ubuntu 11.10 is very slow in DELL INSIRON,with Intel i5,memory 500+4+1GB?Is it a Wubi installation? May 4 comment Finding where the slope of tangent line is = 1@Jordan. Yes it's possible. But I'm afraid that you need to "find" the derivative again. May 4 comment Find recursive formula for definite integralAnyway I am getting a stupid result that doesn't seem right: $$\frac32I_n(x)=I_{n-1}(x)+I_{n+1}(x)-\frac12\frac x{(x^2+1)^{n-1}}$$ May 4 comment Let the random point (X,Y) be uniformly distributed on the unit disc $D=\{(x,y):x^{2}+y^{2}<1\}$To prove independency you need to show that $$P\left[R=r\wedge\Theta=\theta\right]=P\left[R=r\right] P\left[\Theta=\theta\right]$$ May 3 awarded Supporter May 3 answered Difference between Unity and 2D May 3 answered How can I remove Ubuntu from my system and install the Windows bootloader? May 3 answered Let $(X,Y)$ be continuous with density $f(x,y)=Ce^{-x-2y}$ for $x\geq 0$, $y\geq 0$ and $0$ elsewhere. May 2 revised How to interpret "a Poisson distributed random variable approximates a binomial distributed one"?added 394 characters in body