求F2A*F2B的取值范围
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ä¾é¢æ设(x1,y1) (x2,y2)
å(y1-y2)/(x1-x2)=-1/2*(x1+x2)/(y1+y2)
å³k=1/4m
æ æ¹ç¨ä¸ºy-m=(x+1/2)/4m
èç«æ¤åæ¹ç¨åå³å¯æ±åºæå¼
å¦æä¸æï¼å¯è¿½é®ï¼
ä¾é¢æ设(x1,y1) (x2,y2)
å(y1-y2)/(x1-x2)=-1/2*(x1+x2)/(y1+y2)
å³k=1/4m
æ æ¹ç¨ä¸ºy-m=(x+1/2)/4m
èç«æ¤åæ¹ç¨åå³å¯æ±åºæå¼
å¦æä¸æï¼å¯è¿½é®ï¼
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