解题思路:解答:解:设M(x,y),∵F 1 (-1,0),F 2 (1,0),∴由定义知|MF 1 |=-[(x+1)
+y
],|MF 2 |=-[(x-1)
+y
],因为
2 ,那么可知∴(x+1) 2 +y 2 +2(x+1)×y×
=(x-1) 2 +y 2 +2(x-1)×y×
,整理得
7 ,故答案为D。
D
<>
解题思路:解答:解:设M(x,y),∵F 1 (-1,0),F 2 (1,0),∴由定义知|MF 1 |=-[(x+1)
+y
],|MF 2 |=-[(x-1)
+y
],因为
2 ,那么可知∴(x+1) 2 +y 2 +2(x+1)×y×
=(x-1) 2 +y 2 +2(x-1)×y×
,整理得
7 ,故答案为D。
D
<>