[tex]Use\ (ab)^n=a^nb^n\\\\(-3y)^4=(-3)^4y^4=81y^4\\\\(2ax)^3=2^3a^3x^3=8a^3x^3\\\\(10xy)^2=10^2x^2y^2=100x^2y^2\\\\(-2abx)^4=(-2)^4a^4b^4x^4=16a^4b^4x^4\\\\(-am)^3=(-1am)^3=(-1)^3a^3m^3=-1a^3m^3=-a^3m^3\\\\(-xn)^4=(-1xn)^4=(-1)^4x^4n^4=1x^4n^4=x^4n^4[/tex]