1a.
Show from first principles, i.e., by using the definition of linear independence,
that if μ = x + iy, y ̸= 0 is an eigenvalue of a real matrix
A with associated eigenvector v = u + iw, then the two real solutions
Y(t) = eat(u cos bt − wsin bt)
and
Z(t) = eat(u sin bt + wcos bt)
are linearly independent solutions of ˙X = AX.
1b.
Use (a) to solve the system (see image)
Reduce the system
(D2 + 1)[x] − 2D[y] = 2t
(2D − 1)[x] + (D − 2)[y] = 7.
to an equivalent triangular system of the form
P1(D)[y] = f1(t)
P2(D)[x] + P3(D)[y] = f2(t)
and solve.