1、9x^2m-3x^m
=3x^m(x^2-1)
=3x^m(3x^m-1)
2、∵a+b=2,ab=-1/2
∴a(a+b)(a-b)-a(a+b)^2
=a(a+b)(a-b-a-b)
=a(a+b)(-2b)
=-2ab(a+b)
=-2*(-1/2)*2
=2
3、∵a^2+a+1=0
∴a^3+2a^2+2a+1
=a^3+a^2+a+a^2+a+1
=a(a^2+a+1)+a^2+a+1
=(a^2+a+1)(a+1)
=0*(a+1)
=0
∴a^2001+a^2002+...+a^2009
=a^2001(1+a+a^2+...+a^8)=a^2001[(1+a+a^2)+(a^3+a^4+a^5)+(a^6+a^7+a^8)]
=a^2001(1+a+a^2)(1+a^3+a^6)
=0