B/(A+2)=7/9B/(A+3)=3/4
因为△AOB~△BOC,所以AO/OB=BO/OC所以,其中AO=9/4,BO=3,解得OC=4即C坐标为(4,0)将A.C两点代入y=ax^2bx3,解得a=-1/3,b=7