1.
(xy^4)^m
=x^m*y^(4m)…………（x的m次方*y的4m次方）
2.
-(p^2q)^n
=-p^(2n)*q^n
3.
(xy^3n)^2+(xy^6)^n
=x^2y^(6n)+x^n*y^(6n)
=y^(6n)*(x^2+x^n)
4.
（-3x^3)^2-{(2x)^2}^3
=9x^6-(2x)^6
=9x^6-2^6*x^6
=9x^6-64x^6
=-55x^6