int mainO 《程序设计》 cs.stu20119 double a, b dIt, integral =0 cou<<"请输入定积分的区间 cin>>a>>b cou<<"请输入小矩形的度: cin > dIt: for(double x=a dlt /2;x< b;x+= dlt integral +=(x*x+5*X+1)*dIts cout<"积分值为:"<< integral<<end return 0 程序设计-《程序设计》 cs.sjtu 2011.9 程序设计 - 9 int main() { double a, b, dlt, integral = 0; cout << "请输入定积分的区间：" ; cin >> a >> b; cout << "请输入小矩形的宽度：" ; cin >> dlt; for (double x = a + dlt / 2; x < b; x += dlt) integral += (x * x + 5 * x + 1) * dlt; cout << "积分值为：" << integral << endl; return 0; }