抛物线x²+8y＝0的焦点坐标是 A(0,2) B(0,-2) C(0,4) D抛物线x²+8y＝0的焦点坐标是 A(0,2) B(0,-2) C(0,4) D(0,-4)

抛物线x²+8y＝0的焦点坐标是 A(0,2) B(0,-2) C(0,4) D抛物线x²+8y＝0的焦点坐标是 A(0,2) B(0,-2) C(0,4) D(0,-4)
抛物线x²+8y＝0的焦点坐标是 A(0,2) B(0,-2) C(0,4) D
抛物线x²+8y＝0的焦点坐标是 A(0,2) B(0,-2) C(0,4) D(0,-4)

抛物线x²+8y＝0的焦点坐标是 A(0,2) B(0,-2) C(0,4) D抛物线x²+8y＝0的焦点坐标是 A(0,2) B(0,-2) C(0,4) D(0,-4)
X²=-8y
(0,-8/4)=(0,-2)
选B

化为标准方程：x²=-8y
焦点为(0,-2)，选B