Hi, Im just having a little trouble with differential equations. I have y'' - 6y' + λy = 0 I know I need complex roots and setting e^[itex]\alpha[/itex]x gives [itex]\alpha[/itex]= 3+/-sqrt(9 - λ). Then I don't understand why set -ω^2= 9-λ. How do you know if it is -ω^2 or w^2. Thanks for the help.