3) b²+bc+ab+ac = (b²+ab)+(bc+ac) = b(b+a)+c(b+a) = (b+c)(b+a) при a=-1, b=-2, c=-0,5 , тогда (-2-0,5)(-2-1) = -2,5*(-3) = 7,5
4xy+8x-6-3y= 4x(y+2)-3(2+y)= (y+2)*(4x-3)
!!!!!!!!!!!!!!!!!!!!!!!