A:13
B:23
C:1
D:32
有5个连续自然数的和是135,这5个连续自然数是____.(从小到大填写)
—Sorry, Miss Liu. I forgot __________ my homework to school.
— __________ so careless, Sandy.
在平面直角坐标系xOy中,点P到两点(0,-3),(0,3)的距离之和等于4,设点P的轨迹为C.
(1)写出C的方程;
(2)设直线y=kx+1与C交于A、B两点,k为何值时OA→⊥OB→?