Good evening ,
Explanation:
we know that, x-1 = (-1)×(1-x) and 1-x=(-1)×(x-1)
then each of 1-x and x-1 is a multiple of the other one,
if x>1 then x-1>0 and 1-x<0 then x-1>1-x
therefore in this case the least common multiple of x-1 and 1-x is x-1.
if x<1 then x-1<0 and 1-x>0 Then 1-x>x-1
therefore in this case the least common multiple of x-1 and 1-x is 1-x.
:)