Recent content by Brucezhou

This seems easy but when I tried to do this, the best way I came up with is to list all entries and then do the multiplication work. Is there any better ,clearer and more simple way to do the proof?

Group is in the next chapter. Thank you very much. I am learning that chapter.

Homework Statement In the text, the products pq and qp of the permutations (2 3 4) and (1 3 5) were seen to be different. However, both products turned out to be 3-cycles. Is this an accident? Homework Equations p=(3 4 1)(2 5) q=(1 4 5 2) where p and q are permutations The Attempt at a...

Thank you a lot. I have solved. First my Torque equation is wrong. It should be 1/2 WL cos(sita) since the weight is exerted in the middle. Then it should be 2/3*a(tangent)=g*cos(sita) 2/3*cos(sita)*a(tangent)=g*cos^2(sita) cos(sita)*a(tangent)=a(vertical to ground) which should be at least...

weight

Could you suggest a way to solving the problem? I don't have a standard answer key and I don't know where I got wrong. I have published my method above

Let Wr cos(sita)=1/3 mr^2* dw/dt. Simplify it then get: 3g*cos(sita)=r*dw/dt

The question is the first part of Question 63. It is required to make a proof. What I was trying to do is to build a equation with Torque= Moment of Inertia * angular acceleration. But when it was simplified to 3g cos(sita)= r* dw/dt, it seems not easy to solve it, since both of sita and dw/dt...

A professor in Cambridge University has showed his proof that the sum of natural number was equal to -1/12. The video can be found on the internet.Well, although the way to proof I think is really ridiculous, it could be a good way to building a new math model. Since we think the sum of natural...

I think I have to explain what I said in the question. Bernoulli method and integrating factor don't work since I've tried several times but failed. And now I don't want others to waste too much time in these two ways, so I typed those words. But if someone finds this question can be solved...

The question is to find the function involving variables x and y.

dy/dx=2x+y^2 By the way, methods of solving linear differential equation are useless, such as integrating factor and Bernoulli method.

I mean the application,such as because of the time dilation, humans can observe some particles which don't have long lifetime,and know it

Well, I'm totally in a mess now

But how to explain that phenomenon