For which value(s) of kkk does the system {(k−1)x+2y=53x+(k+1)y=7\begin{cases} (k-1)x + 2y = 5 \\ 3x + (k+1)y = 7 \end{cases}{(k−1)x+2y=53x+(k+1)y=7 have a unique solution?
k=±7k = \pm\sqrt{7}k=±7
k≠±7k \neq \pm\sqrt{7}k=±7
k>0k > 0k>0
All real kkk