Show that if n>r>0, the complementary function represents vibrations which are ultimately damped out. Further, prove that the particular integral is of the form bcos(pt-α), where b^2= a^2/[(n^2-p^2)^2 +4r^2p^2].
The differential equation
(1-x^2)(∂^2z/∂x^2 -2xy[∂^2z/(∂x.∂y)] + (1-y^2)(∂^2z/∂y^2) + 2(∂z/∂x) +3y(∂z/∂y)=0, is elliptic for (x,y) outside the circle x^2 + y^2=1
True or false with correct explanation