А) =11(m-1)(m+1)
б) = 6a(a-1)(a+1)
в) =5x(x-y)(x+y)
г) =8a²(b-3c)(b+3c)
д) =2(x+6y)²
е) =(x+y)²-7²=(x+y-7)(x+y+7)
ж) =a²-(9b²-6bc+c²)=a² -(3b-c)²=(a-3b+c)(a+3b-c)
з) =(x³y²-x³)-(xy-x)=x³(y²-1)-x(y-1)=x³(y-1)(y+1)-x(y-1)=
=x(y-1)(x²(y+1)-1)=x(y-1)(x²y+x²-1)
и) =(a²+2ab+b²)-(c²-4cd+4d²)=(a+b)²-(c-2d)²=(a+b-c+2d)(a+b+c-2d)
к) =(a²+4a+4)-b²=(a+2)²-b²=(a+2-b)(a+2+b)