I understand how the -x turns into (-1)x. How does 1-x turn into (-1)(x-1)?
Put it this way, you can interpret it as (1-x) is divided by -1
(1-x) = (-x +1 ) just switching position keeping the signs
(-x+1)= -1(x-1 )
I still don’t understand…
Oh thank you Kremlin! Got it.