Question

下列方程:①3x^2+1=0 ②根号2x^2-根号3x+1=0

Answer 1

1①,②都是

故选B

2 由题知

m^2-2m-1=0

n^2-2n-1=0

且m+n=-b/a=2

mn=-1

即m^2-2m=1

n^2-2n=1

即3m^2-n^2-8m+1

=3m^2-6m-n^2-2m+1

=3(m^2-2m)-n^2-2m+1

=3-n^2-2m+1

=-n^2-2m+4

=-n^2+2n-2n-2m+4

=-（n^2-2n）-2（m+n）+4

=-1-2×2+4

=-1