(2x+11)^2=4x^2+44x+121
m=44
(x+2)^2+(y-3)^2=0,x=-2,y=3
(x+2y)(x-2y)=x^2-4y^2=4-4*9=-32
a^2-2a+5=(a-1)^2+4 最小=4,a=1