(x-3)(ax+1)=ax*ax+2x+b x*ax+x-3ax-3-(ax*ax+2x+b)=0 (a-a*a)x*x+(1-3a-2)-(3+b)=0所以：a-a*a=0, 1-3a-2=0, 3+b=0,解得：a=-1/3,b=-3
