(-∞,-3 ∪ 1,+∞)
(-∞,-3 ∪ 1,+∞) 提示
设 P ( t , t 2-1), Q ( s , s 2-1),∵ BP ⊥ PQ ,
∴ =-1,即 t 2+( s -1) t - s +1=0,
∵ t ∈R,∴必须有 Δ =( s -1) 2+4( s -1)≥0
即 s 2+2 s -3≥0,解得 s ≤-3或 s ≥1