x的初值不能是0，请修改
clear allclc
dy=@(t,y)([y(2); 61.3*y(3)-55.9*y(4)-10.7; 4.1/y(1)-6.3/y(1)*y(2); 1.4/(75-y(1))*y(2)-4.5/(75-y(1))]);[t,Y]=ode45(dy,[.1 1],[1 2 4.5 1]);plot(t,Y(:,2)),legend('dx/dt')
