Question

Looking for the solution to equations of the form y''+y=0

Answer 1

sinx, cosx?

Answer 2

If y'' is proceded by a constant?

Answer 3

y=Csinx and y=Ccosx......anybody?

Answer 4

There is an e^ax factor before the trig functions, where a is a root of the characteristic equation. Should be something like y = ce^ax sinx + ce^ax cosx.

Answer 5

That rings a bell, happen to know of a good tutorial/reference?

Answer 6

http://tutorial.math.lamar.edu/Classes/DE/ComplexRoots.aspx

Answer 7

hope that helps.

Answer 8

Great stuff, cheers matey.

Answer 9

cheers

Answer 10

this is the generic equation, but since
\[y=e^{ax}[C_{1}\cos(x)+C_{2}\sin(x)]\rightarrow a=0\]
this will be you final equation
\[y=C_{1}\cos(x)+C_{2}\sin(x)\]