(3x+y)(2x-5y)-6(x-y)^2= 6x^2 - 15xy + 2xy - 5y^2 -6(x^2 - 2xy + y^2)= 6x^2 - 15xy + 2xy - 5y^2 - 6x^2 + 12xy - 6y^2= -9xy - 11y^2
(-2x^3y)^3(-5x^2y)^2= (-8x^9y^3)(-25x^4y^2)= 200x^13*y^5
(-x^2y^3)^3(-2x^5y)^2= (-x^6y^9)(-4x^10y^2)= 4x^16*y^11
(3x+y)(2x-5y)-6(x-y)^2
= 6x^2 - 15xy + 2xy - 5y^2 -6(x^2 - 2xy + y^2)
= 6x^2 - 15xy + 2xy - 5y^2 - 6x^2 + 12xy - 6y^2
= -9xy - 11y^2
(-2x^3y)^3(-5x^2y)^2
= (-8x^9y^3)(-25x^4y^2)
= 200x^13*y^5
(-x^2y^3)^3(-2x^5y)^2
= (-x^6y^9)(-4x^10y^2)
= 4x^16*y^11