kramer.cpp

#include<iostream>
using namespace std;
int main() {
	double a[3][3];
	double b[3];
	for (int i=1; i<4; i++) {
		for (int j=1; j<4; j++) {
			cout << "Enter left side coeficients" << endl;
			cout << "a[" << i << "," << j << "]=";
			cin >> a[i][j];
		}
			cout << "Enter right side coeficients" << endl;
			cout << "b[" << i << ",4]=";
			cin >> b[i];
	}
	double det, detx, dety, detz;
	det = a[1][1]*(a[2][2]*a[3][3]-a[3][2]*a[2][3])+a[1][2]*(a[2][1]*a[3][3]-a[3][1]*a[2][3])+a[1][3]*(a[2][1]*a[3][2]-a[3][1]*a[2][2]);
	detx = b[1]*(a[2][2]*a[3][3]-a[3][2]*a[2][3])+a[1][2]*(b[2]*a[3][3]-b[3]*a[2][3])+a[1][3]*(b[2]*a[3][2]-b[3]*a[2][2]);
	dety = a[1][1]*(b[2]*a[3][3]-b[3]*a[2][3])+b[1]*(a[2][1]*a[3][3]-a[3][1]*a[2][3])+a[1][3]*(a[2][1]*b[3]-a[3][1]*b[2]);
	detz = a[1][1]*(a[2][2]*b[3]-a[3][2]*b[2])+a[1][2]*(a[2][1]*b[3]-a[3][1]*b[2])+b[1]*(a[2][1]*a[3][2]-a[3][1]*a[2][2]);
	if (det==0 && detx==0 && dety==0 && detz==0) {
	cout << "The system have infinity nubers of equation";
	}
	else if (det==0) {
	cout << "The system have no equations";
	}
	else {
	double x[3];
	x[1] = det/detx;
	x[2] = det/dety;
	x[3] = det/detz;
	for (int i=1; i<4; i++) {
	cout << "x[" << i << "]=" << x[i] << endl;
	}
	}
	system("pause");
	return 0;
}