Recent content by Buddy711

For a traveling wave u(x,t) = u(x-ct) How is the relation below hold? u_{x}u_{xt}=-u_tu_{xx} I don't understand why there is (-) sign . Thanks in advance ! PS. Here is the URL of the book I am having trouble with https://www.amazon.com/dp/0198528523/?tag=pfamazon01-20...

I want to show that if the energy is the integral : E = \frac{1}{2} \int^{\infty}_{-\infty} u_{t}^2 \ dx then the derivative of the energy with respect to time t is \frac{dE}{dt} = - \int^{\infty}_{-\infty} u_{xt}^2 + f'(u) u_{t}^2 \ dx What is the first step can you...

hi all. I am very confusing there exists such a convergent number of this equation. x[n] = 0.5(x[n-1]+x[n-2]) with the initial value x[0]=3, x[1]=5 if n goes infinity, x[n] may go to 13/3. How can I approach this problem? thanks.

You are absolutely right. I was so stupid. Thank you ;-)

You suggested me very good approach. However, the problem still remains,,, my equation is n vs (n-2), not n vs (n-1) Thanks!

Hi everyone. I hardly remember the fomulas of summation of sequence. I got this problem. {\frac{1}{8}}\sum^{\infty}_{n=2}n({\frac{3}{4}})^{n-2} The result is 2.5. How can I solve this problem? Thanks all. :)