#include "stdio.h"#include "math.h"main(){double a,b,c,x1,x2,dt,p,q;printf("please input a,b,c:");scanf("%lf%lf%lf",&a,&b,&c);if(b*b-4*a*c>=0){dt=sqrt(b*b-4*a*c);p=-b/(2*a);q=dt/(2*a);x1=p+q;x2=p-q;pr...