Question

                 dùng c++

Answer 1

#include <bits/stdc++.h>

using namespace std;

// Hàm tính tổng 1 + 2 + ... + k

double tong(int k) {

return k * (k + 1) / 2.0;

}

// S1

double S1(int n) {

double s = 0;

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

s += 1.0 / tong(i);

return s;

}

// S2

double S2(int n) {

double s = 0;

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

s += pow(i, n);

return s;

}

// S3

double S3(int x, int n) {

double s = 0;

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

s += pow(x, i) / tong(i);

return s;

}

// S4

double S4(int x, int n) {

double s = 0, gt = 1;

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

gt *= i;

s += pow(x, i) / gt;

}

return s;

}

// S5

double S5(int x, int n) {

double s = 0, gt = 1;

for (int i = 1; i <= 2 * n + 1; i++) {

gt *= i;

if (i % 2 == 1) {

int k = (i - 1) / 2;

if (k < n)

s += pow(x, i) / gt;

}

}

return s;

}

int main() {

int x, n;

cin >> x >> n;

cout << fixed << setprecision(2) << S1(n) << endl;

cout << fixed << setprecision(1) << S2(n) << endl;

cout << fixed << setprecision(1) << S3(x, n) << endl;

cout << fixed << setprecision(1) << S4(x, n) << endl;

cout << fixed << setprecision(1) << S5(x, n) << endl;

return 0;

}