ac-bc-〖bc〗^2+〖ac〗^2-a+b=
=c(a-b)+c^2(a^2-b^2)-(a-b)=
=c(a-b)+c^2(a-b)(a+b)-(a-b)=
=(a-b)(c+c^2(a+b)-1)
ac-bc-〖bc〗^2+〖ac〗^2-a+b=
=c(a-b)+c^2(a^2-b^2)-(a-b)=
=c(a-b)+c^2(a-b)(a+b)-(a-b)=
=(a-b)(c+c^2(a+b)-1)