求实数x分别取什么值时,复数z=lg(x2-2x-2)+(x2+3x+
2)i是:(1)实数;(2)纯虚数.
(1) x=-1或x=-2. (2) x=3
(1)要使z是实数,必须且只需解得x=-1或x=-2.
(2)要使z是纯虚数,必须且只需解得x=3.
求实数x分别取什么值时,复数z=lg(x2-2x-2)+(x2+3x+
2)i是:(1)实数;(2)纯虚数.
(1) x=-1或x=-2. (2) x=3
(1)要使z是实数,必须且只需解得x=-1或x=-2.
(2)要使z是纯虚数,必须且只需解得x=3.