编辑代码

#include <stdio.h>
#include <math.h>
//double y(double x);
int main () {
    double x1,x2;
    int n;
    scanf("%d",&n);
    scanf("%lf %lf",&x1,&x2);
    double dx=(x2-x1)/n;
    double sum=0;
    double numsy[n];
    for(int i=0;i<n;i++){
        numsy[i]=sin(2*x1)+x1;
        sum+=numsy[i]*dx;
        x1+=dx;
    }
    printf("%lf",sum);
}

//double y(double x){
    //y=sin(2*x)+x;
    //return y;
//}