3.1.1if语句 cout<<"输入三个系数a(a!=0),b,c:"<<end 入三个系数a(a!=0),b,c: cin>>a>>b>>c: 144 cout<<"a="<<a<<"t'<<"b="<<b<<"t"<<"c="<<c<<endl delta=b**c a=1b=4c=4 if(fabs(deta)<zero){∥绝对值很小的数即被认为是0 dela=4*44*1*4=0 cou<"方程有两个相同实根:"; cout<<x1=x2=<<-b/(2*)<<endl 方程有两个相同实根: x1=x2=4/(2*1)=-2 else if(delta>0)f delta= sqrt(delta); xl=(-b+delta)/(2*a) x2=(-b-delta)/(2*a); cout<<"方程有两个不同实根 cout<<"xl="<x1<<"'<"x2="<<x2<<endl els //deltas 岗心國 cout<"方程无实根!;}3.1.1 if 语句 cout<<"输入三个系数a(a!=0),b, c:"<<endl; cin>>a>>b>>c; cout<<"a="<<a<<'\t'<<"b="<<b<<'\t'<<"c="<<c<<endl; delta=b*b-4*a*c; if(fabs(delta)<zero){ //绝对值很小的数即被认为是0 cout<<"方程有两个相同实根:"; cout<<"x1=x2="<<-b/(2*a)<<endl; } else if(delta>0){ delta=sqrt(delta); x1=(-b+delta)/(2*a); x2=(-b-delta)/(2*a); cout<<"方程有两个不同实根:"; cout<<"x1="<<x1<<'\t'<<"x2="<<x2<<endl;} else //delta<0 cout<<"方程无实根!";} 输入三个系数a(a!=0),b,c: 1 4 4 a=1 b=4 c=4 delta=4*4-4*1*4=0 方程有两个相同实根: x1=x2=-4/(2*1)=-2