f.2數學-factorization

ax-a-x+1

=a(x-1) -(x-1)

= (a-1)(x-1)

because -(x-1)=-x+1
if we change to this factor
then the whole factorization will have common factor (x-1)
抽common factor就完成~

ax-a-x+1
=a(x-1)-(x-1)
=(a-1)(x-1)
留意-號
because 負
負得正，所
以-x+1 應該
變成-(x-1)

ax-a-x+1
=a(x-1)-(x-1)
=(a-1)(x-1)

ax-a-x+1
=a(x+1)-(x+1)
=(x+1)(a-1)