(-5xy^3)^2 = (-5)^2 (x)^2 (y^3)^2=(-5)^2 x^2 y^6= 25x^2y^6
Поэтому,
12x^4y^5 (-5xy^3)^2= 12x^4y^5 25x^2y^6= 300x^6y^11
(-5xy^3)^2 = (-5)^2 (x)^2 (y^3)^2
=(-5)^2 x^2 y^6
= 25x^2y^6
Поэтому,
12x^4y^5 (-5xy^3)^2
= 12x^4y^5 25x^2y^6
= 300x^6y^11