# Thread: diff eqn, level 5?

1. ## diff eqn, level 5?

I have no idea how to even start, let alone anything else... but even if i had, i bet i would get stuck somewhere in it.

d5y/dx5 + 2(d4y/dx4)+ d3y/dx3 + 3(d2y/dx2) -y=0

given y(0)=dy/dx(0)=d2y/dx2(0)=d3y/dx3(0)=d4y/dx4(0)=0. this looks horrible...auch

2. Originally Posted by fiksi
I have no idea how to even start, let alone anything else... but even if i had, i bet i would get stuck somewhere in it.

d5y/dx5 + 2(d4y/dx4)+ d3y/dx3 + 3(d2y/dx2) -y=0

given y(0)=dy/dx(0)=d2y/dx2(0)=d3y/dx3(0)=d4y/dx4(0)=0. this looks horrible...auch
Well this is a fifth order linear constant coefficient ODE, and with adequate initial conditions the solution is unique, also the zero function satisfies the equation and initial conditions. So ...

CB

3. Originally Posted by CaptainBlack
Well this is a fifth order linear constant coefficient ODE, and with adequate initial conditions the solution is unique, also the zero function satisfies the equation and initial conditions. So ...

CB
Well, so is it since all derivatives of 0, and y(0) all equal zero, the final solution is y=0?

4. Originally Posted by fiksi
Well, so is it since all derivatives of 0, and y(0) all equal zero, the final solution is y=0?
Yes, thats what he said.