find the value of k such that the system has infinite number of solutions

(k-1)x - y = 5

(k+1)x + (1-k)y = (3k+1)

plzz solve it wholly

thnks in advance

i am aquinted with the process of taking 3 cases and show the common value of k in all is the answer. so it will be helpful if u solve it with this process. i am having problem with factorising so plzz solve it wholly.