Apply the eigenvalue method to find the solution to the system of differential equations which satisfies the initial conditions.
a) {dy/dx} = 3y , {dz/dx} = 4z ; y(0) = 1, z(0) = 2
b) {dx/dt} = -2x , {dy/dt} = 5y ; x(0) = 1, y(0) = 2
c) {du/dt} = 2u , {dv/dt} = -6v ; u(0) = 1, v(0) = 3
d) {dw/dt} = 7w , {dz/dt} = -8z ; w(0) = 2, z(0) = 4
