Answer:
k = (1 , 4)
Explanation:
 here's your solution
==> k^2 - 5k + 4. [ is expression ]
 ==> by using middle term split
 ==> k^2 - 4k - k + 4 
 ==> taking common from each
 ==> k(k - 4) - 1 (k - 4)
 ==> (k - 1) , (k - 4). 
 ==> k - 1 = 0
 ==> k = 1
 ==> k - 4 = 0
 ==> k = 4
 hence , k = (1 , 4)
 hope it helps