# 4th order DE

by zoom1
Tags: order
 Math Emeritus Sci Advisor Thanks PF Gold P: 39,533 Great! For those who are interested, though, let me note that since $-2+3i$ and $-2-3i$ are roots then $(x- (-2+3i))(x-(-2-3i))= (x+2- 3i)(x+2+ 3i)= (x+2)^2- (3i)^2= x^2+ 4x+ 4+ 9= x^2+ 4x+ 13$. Now divide $x^4+ 6x^3+ 22x^2+ 30x+ 13$ by that to find the quadratic equation the other roots must satisfy.