function  z=dfnv3p5(t,y);
%% derivative with respect to t of the function f(t,y(t)) found in
%% Burden and Faires Chap 5 Sect 3 problem 5
z=-2*(t.^(-2)).*y +2*(t.^(-1)).*fnv3p5(t,y)+(t.^2+2*t).*exp(t);
