证明:∵x²+2kx+k-1=0
∴a=1 b=2k c=k-1
Δ=b²-4ac=4k²-4﹙k-1﹚
=4k²-4k+4
=4k²-4k+1+3
=﹙2k-1﹚²+3≥3
∴方程有两个不相等的实数根