x＋y＋2x－8y＋17＝0 x^2+2x+1+y^2-8y+16=0 (x+1)^2+(y-4)^2=0 (x+1)^2>=0 (y-4)^2>=0 所以 (x+1)^2=0 (y-4)^2=0 x=-1,y=4 x^2009+xy =-1-4=-5