Find the solution of y =-k^2*y , y(0)=1 y'(0)=0?

[mikehsiao789]

Find the solution of y"=-k^2*y , y(0)=1 y'(0)=0?

Homework Statement

Find the solution of y"=-k^2*y , y(0)=1 y'(0)=0?

Homework Equations

y"=-k^2*y , y(0)=1 y'(0)=0?

The Attempt at a Solution

I've been stuck on this problem for a while but I can't seem to get it. I used the method of making it into a characteristic equation, but I got +/- ki for R but that doesn't seem to work. Thanks in advance for your help!

 

[SteamKing]

Why doesn't it work? Show your calculations.

 

[arildno]

"got +/- ki for R but that doesn't seem to work."

It does work.