2.過(0,0)、(6,0)、(0, - 8)三點之圓方程式為 (A)(x + 6)2 + (y - 8)2 = 1 (B)x2 + y2 - 12x + 16y + 10 = 0 (C)x2 + y
4.若方程式x2 + y2 + 2kx - 6y + (k2 + k + 1) = 0的圖形為一點,則此點坐標為 (A)(4 , 3) (B)( - 4 , 3) (C)( - 8 , 3) (D)(
8.拋物線的準線y = 0、焦點(0, - 8),則其方程式為 (A)x2 = - 16(y + 4) (B)x2 = - 4(y + 8) (C)x2 = - 8(y + 4) (D)y2 = 16