Therefore, when x= 1/2 and y=-2/3, the minimum value of the polynomial 4x 2+9y 2-4x+ 12y-1 is -6.

Because a=20 10x+20 10, b=20 10x+20 12, c=20 10x+20 13,

So b-a=2 c-a=3 c-b= 1.

Therefore, a 2+b 2+c 2-ab-BC-ca =1/2 * [(b-a) 2+(c-a) 2+(c-b) 2] =1/2 * (4+).

Because (2016-a) (2011-a) = 986,

so(20 16-a)2+(20 1 1-a)2 =(20 16-a)2-2(20 16-a)(2065438+)

=[(20 16-a)-(20 1 1-a)]^2+2*986

=25+ 1972= 1997