几道二元一次方程1.2002x^2+2003x+1=02.(m-2)x^2-(m+3)x-2m-1=03.(m^2-25)x^2-2m^2 x+m^2=0

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几道二元一次方程1.2002x^2+2003x+1=02.(m-2)x^2-(m+3)x-2m-1=03.(m^2-25)x^2-2m^2 x+m^2=0
几道二元一次方程
1.2002x^2+2003x+1=0
2.(m-2)x^2-(m+3)x-2m-1=0
3.(m^2-25)x^2-2m^2 x+m^2=0

几道二元一次方程1.2002x^2+2003x+1=02.(m-2)x^2-(m+3)x-2m-1=03.(m^2-25)x^2-2m^2 x+m^2=0
1.2002x^2+2003x+1=0
(2002x+1)(x+1)=0
x1=-1/2002,x2=-1
2.(m-2)x^2-(m+3)x-2m-1=0
判别>=0,m>=1/3
m=2,m≠-3,x=-(2m+1)/(m+3)
m≠2,m>=1/3
[(m-2)x-(2m+1)](x+1)=0
x=(2m+1)/(m-2),x2=-1
3.(m^2-25)x^2-2m^2 x+m^2=0
m^2-25=0,m=±5,m≠0,x=1/2
m≠±5,判别>=0,m≠±5的任意
[(m+5)x-m])[(m-5)x-m]=0
x1=m/(m+5),x2=m/(m-5)