Recent content by nowak

I know, I only knew how to solve for the two of them. I tried to find the other two using the reduction of order method and was unable to get the answer the book said.

I said r^2(r^2)=0 so I took the first root to be (0+i) and the second to be (0-i), from there I can say y=e^(0)(Ccosx+C'sinx). I was unsure how to get the other two roots from there. Tried reduction of order saying that if y_1=cosx then v_1y_1=y_3 but this does not give the answer in the book.

Homework Statement y^(4)+y=0 Homework Equations Need to use de Moivre's formula to obtain answer. 3. The Attempt at a Solution . I can obtain the characteristic equation r^4=-1. From there I tried saying y_1 = cosx and y_2=sinx. However, my book has the answer listed as y=...