2.13
A) cin >> b >> c >> d >> e >> f;

2.14
E) a * (x * x * x) + ;

2.21
#include<iostream>
using namespace std;
int main()
{
cout<<"*********\n*       *\n*       *\n*       *\n*       *\n*       *\n*       *\n*       *\n*********\n\n";
cout<<"   ***   \n *     * \n*       *\n*       *\n*       *\n*       *\n*       *\n *     * \n   ***   \n\n";
cout<<"  *  \n *** \n*****\n  *  \n  *  \n  *  \n  *  \n  *  \n  *  \n\n";
cout<<"    *    \n   * *   \n  *   *  \n *     * \n*       *\n *     * \n  *   *  \n   * *   \n    *    \n\n";
return 0;
}

2.30
#include<iostream>
using namespace std;
int main()
{
	int weight = 0, height = 0, BMI = 0;
	cout << "How much do you weigh in pounds?";
	cin >> weight;
	cout << "What is your height in inches?";
	cin >> height;
	BMI = ((weight * 703)) / ((height * height));
	cout << "Your BMI is" << BMI;
	if (BMI <= 18.5) {
		cout << "You're underweight\n";
	}
	if ((BMI > 18.5) && (BMI <= 24.9)) {
		cout << "You're Normal\n";
	}
	if ((BMI > 25) && (BMI <= 29.9)) {
		cout << "You're overweight\n";
	}
	if (BMI > 30) {
		cout << "You're obese\n";
	}
}