A) ab+ac-b-c=a(b+c)-(b+c) = (b +c)(a -1)
b) mn-m+n-1 =m(n-1)+(n-1) = (n -1)(m +1)
в) bd-ad+3a-3b= -d(a-b)+ 3(a-b)= (a -b)(-d +3)
г) 2b-2c+ab-ac=2(b-c)+a(b-c)=(b -c)(2 +a)
a) a(x -1) +b(x -1) +c(x -1) = (x -1)(a +b +c)
b) x(a +b) -y(a +b) +z(a -b) = (a +b)(x -y) +z(a -b)