需要matlab编程，所以需要中文帮助来学习！syms t x
ft=t^2*cos(t)
sx=int(ft,t,0,x)   
ft =
t^2*cos(t)
sx =
x^2*sin(x)-2*sin(x)+2*x*cos(x)  

（2）数值计算解法
dt=0.05;
t=0:dt:5;
Ft=t.^2.*cos(t);
Sx=dt*cumtrapz(Ft);
t(end-4:end)
Sx(end-4:end)
plot(t,Sx,'.k','MarkerSize',12)
xlabel('x'),ylabel('Sx'),grid on
ans =
    4.8000    4.8500    4.9000    4.9500    5.0000
ans =
  -20.1144  -19.9833  -19.7907  -19.5345  -19.2131