f(x)=2x²+(x-1)² =3x²-2x+1 (x≥1)f(x)min=2f(x)=2x²-(x-1)²=x²+2x-1 (x<1)f(x)min=-2
①x>=1时f(x)=2x^2+(x-1)^2=3x^2-2x+1=3(x-1/3)^2+2/3当x=1时,取得最小值为2②x<1时f(x)=2x^2-(x-1)^2=x^2+2x-1=(x+1)^2-2当x=-1时,去的最小值为-2综上所述,f(x)的最小值为-2