Show that if y(t) is a solution of y'' + a(t)y = 0, then so is y(t+w), let y1(t) and y2(t) be two linearly independent solutions of y'' +a(t)y = 0 satisfying normalized initial conditions y1(0)=1, y1'(0)=0 ,y2(0)=0 , y2'(0)=1 show that the multipliers satisfy r2 - (y1(w)+y2'(w) )r + 1= 0.