Câu 2 :

#include <iostream>
using namespace std;
int main()
{
    int n, i, j, d;
    cout << "Nhap so n = ";
    cin >> n;
    cout << "Cac so nguyen to : ";
    for (i = 2; i <= n; i ++){
        d = 0;
        for (j = 2; j < i; j++){
            if (i % j == 0) d = 1;
        }
        if (d == 0) cout << i << "  ";
    }
    return 0;
}

Câu 3 :

#include <iostream>
using namespace std;
int main()
{
    float a[100], min, max, s = 0.0;
    int i, n;
    cout << "Nhap so phan tu = ";
    cin >> n;
    cout << "Nhap day gom " << n << " so : ";
    for (i = 0; i < n; i++) cin >> a[i];
    max = a[0]; min = a[0];
    for (i = 0; i < n; i++){
        if (a[i] > max) max = a[i];
        if (a[i] < min) min = a[i];
        s = s + a[i];
    }
    cout << "Gia tri lon nhat = " << max << endl;
    cout << "Gia tri nho nhat = " << min<< endl;
    cout << "Trung binh day so = " << s / (n * 1.0);
    return 0;
}

Câu 2,

#include<iostream>

using namespace std;

int main(){

int n;

cin>>n;

for(int i=2;i<=n;i++){

int dem=0;

for(int j=1;j*j<i;j++){

if(i%j==0){

dem++;

}

}

if(dem==1){

cout<<i<<" ";

}

}

}

Câu 3,

#include<bits/stdc++.h>

using namespace std;

int main(){

int n;

cin>>n;

float a[n],t=0;

for(int i=1;i<=n;i++){

cin>>a[i];

t+=a[i];

}

float tb=t/n;

cout<<*min_element(a,a+n+1)<<" "<<*max_element(a,a+n+1)<<endl;

cout<<tb<<endl;

for(int i=1;i<=n;i++){

if(a[i]<tb){

cout<<a[i]<<" ";

}

}

cout<<endl;

for(int i=1;i<=n;i++){

if(a[i]>tb){

cout<<a[i]<<" ";

}

}

}