a^2-ab+1/4*b^2+3/4*b^2-3*b+c^2+4*c+7=0(a-1/2*b)^2+3*(1/4*b^2-b+1-1)+c^2+4*c+7=0(a-1/2*b)^2+3*(1/2*b-1)^2-3+(c+2)^2+3=0(a-1/2*b)^2+3*(1/2*b-1)^2+(c+2)^2=0故a-1/2*b=0,1/2*b-1=0,c+2=0则a=1,b=2,c=-2故a+b+...