例4.1

#include<math.h> int main() {double a,b,c,disc,x1,x2,p,q; scanf("%if%if%if",&a,&b,&c); disc=b*b-4*a*c; if(disc<0) printf("This equation hasn't real roots\n"); else{ p=-b/(2.0*a); q=sqrt(disc)/(2.0*a);

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