1.x^2+(m+2)x+2m-1=0的两根互为相反数
x1+x2=0
m+2=0
m=-2
x^2-5=0
x=±√5
2.m+n=3,
mn=1,
m=3-n,
mn=3n-n2=1,
n2-3n=-1,
m2+n2=7
原式=2m2+2n2+2n2-6n+1999
=14-2+1997
=2009
1.x^2+(m+2)x+2m-1=0的两根互为相反数
x1+x2=0
m+2=0
m=-2
x^2-5=0
x=±√5
2.m+n=3,
mn=1,
m=3-n,
mn=3n-n2=1,
n2-3n=-1,
m2+n2=7
原式=2m2+2n2+2n2-6n+1999
=14-2+1997
=2009