Нужна помощь с выполнением заданий в C++

#include <cmath>
#include <iostream>
#include <iomanip>
using namespace std;
void task1() {
double i = 5.0;
double k = -2.0;
double x = 0.1;
double a = 25.2;
double b = 2.35;
double ab = pow(a + b, 2);
if (ab != 0) {
double arg = exp(-5.0) * 1e3;
double y = tan(i * k) - (a * pow(x, 3) - b) / ab + arg + cbrt(1e2 * fabs(x * k) / ab);
cout << " y: " << setprecision(15U) << y << '\n';
} else {
puts(" Task 1. Invalid argument!");
}
puts("");
}
double fact(int n) {
return n <= 0? 1 : n * fact(n - 1);
}
void task2() {
constexpr double arg = 3.1415926535897932 / 4.0;
double a = 0.1;
double b = 1.0;
double h = (b - a) / 10.0;
double end = b + h / 10.0;
int n = 120;
for (double x = a; x < end; x += h) {
double s = 0.0;
for (int i = 0; i <= n; ++i)
s += cos(i * arg) / fact(i) * pow(x, i);
double y = exp(x * cos(arg)) * cos(x * sin(arg));
cout
<< setprecision(2U) << setw(5U) << x << ' '
<< setprecision(15U) << setw(25U) << s << ' '
<< setprecision(15U) << setw(25U) << y << '\n';
}
puts("");
}
void task3() {
double sum = 0.0;
for (int i = 0; i <= 10; ++i) sum += pow(-1, i + 1) / fact(i);
cout << " S = " << setprecision(15U) << sum << '\n';
}
int main() {
cout.setf(ios::fixed);
task1();
task2();
task3();
system("pause > nul");
}