8
The equation (k-1)x^2+kx-4=0 has only one solution,
then k^2 - 4(k-1)(-4)=0
k^2+16(k-1)=0
k^2+16k-16=0
k^2+16k+64=80
(k+8)^2=80
k+8= ±sqrt 80
k = -8 ± 4 sqrt 5
Added 12/26/2014 1:15:49 AM
This answer has been confirmed as correct and helpful.
Confirmed by
jeifunk [12/26/2014 2:53:28 AM]