#include <stdio.h>
#include <math.h>
#define EPS 1.0e-5
#define n 4
 
int main(void){
int i,k;
 
double x[n],y[n];
 
double sum_xy=0,sum_x=0,sum_y=0,sum_x2=0;
 
double a=0,b=0;
 
for(i=0;i<n;i++){
printf("X座標を入力[%d]：",i);
scanf("%lf",&x[i]);
printf("Y座標を入力[%d]：",i);
scanf("%lf",&y[i]);
}
 
for(k=0;k<n;k++){
sum_xy+=x[k]*y[k];
sum_x+=x[k];
sum_y+=y[k];
sum_x2+=x[k]*x[k];
}
 
a=(sum_x2*sum_y-sum_xy*sum_x)/(n*sum_x2-sum_x*sum_x);
b=(n*sum_xy-sum_x*sum_y)/(n*sum_x2-sum_x*sum_x);
 
printf("直線ｙ＝(%g)＋(%g)x",a,b);
 
return 0;
}

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MC4wIDEuMAowLjIgMS45CjAuNCAzLjIKMC42IDQuMwo=

0.0 1.0
0.2 1.9
0.4 3.2
0.6 4.3