第一题

#include <iostream>#include <cmath>using namespace std;double q(double,double,double);int main(){double a,b,c,p,x1,x2; cout<<"please enter a,b,c:"; cin>>a>>b>>c; p=-b/(2*a); try  {x1=p+q(a,b,c);   x2=p-q(a,b,c);   cout<<"x1="<<x1<<endl<<"x2="<<x2<<endl;  } catch(double d)   {cout<<"a="<<a<<",b="<<b<<",c="<<c<<",disc="<<d<<",error!"<<endl;} cout<<"end"<<endl;}double q(double a,double b,double c) {double disc;  disc=b*b-4*a*c;  if (disc<0) throw disc;  return sqrt(disc)/(2*a); }

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