00:01
Okay, you really don't say how to solve this equation.
00:04
And i think undetermined coefficients or variation of parameters will be about the same amount of work.
00:11
So i'm going to just do undetermined coefficients.
00:14
So first i've got to solve this.
00:16
M squared plus 4 equals 0.
00:18
So m is plus and minus 2i.
00:22
So y sub c is, okay, that's like 0.
00:25
So c1, e to the 0, t, cosine, cosine 2t plus c2, each.
00:32
To the 0t sine 2t, which is just c1 cosine 2t plus c2 sine 2t.
00:43
All right.
00:44
Then for yp, i have cosine 2t.
00:48
So my guess is a, cosine 2t plus b sine 2t.
00:55
Okay, but that's no good because that's exactly what yc looks like.
01:00
So i'm going to have to multiply it by t so that it's different.
01:06
Okay, so i'll write it like that...