Разложите на множители: х^2у-36у^3 -5m^2+10mn-5n^2 4ab-28b+8a-56 a^4-81

Х^2у-36у^3=y(x-6y)(x+6y)
-5m^2+10mn-5n^2=-5(m-n)²
4ab-28b+8a-56=4b(a-y)+8(a-7)=(a-7)(4b+8)=4(a-7)(b+2)
A^4-81=(a²-9)(a²+9)=(a-3)(a+3)(a²+9)

1)y(x^2-36y^2)=y(x-6y)(x+6y)
2)-5(m-n)^2
3)4(ab-7b+2a-14)=4(a(b+2)-7(b+2))=4(b+2)(a-7)
4)(a^2-9)(a^2+9)=(a-3)(a+3)(a^2+9)