OBOCOA的精选

问题详情：抛物线y=ax2+bx+c与x轴相交于点A与点B,与y轴相交于点C,如果OB=OC=OA,那么b的值为  ()A.-2             B.-1          C.-          D.【回答】C解析由图象可知c>0,且B(c...