-[(-x)^3]^m
=-(-x^3)^m
=-(-1)^m*x^(3m)
所以m是奇数,则=x^3m
m是偶数,则=-x^3m
(-x^2)^4-2x^2*(x^3)^2+(-x^4)^2
=x^8-2x^2*x^6+x^8
=x^8-2x^8+x^8
=0
[（a-b)^n]^2[(b-a)^n-1]^2
=(a-b)^(2n)*(b-a)^(2n-2)
2n-2是偶数
所以=(a-b)^(2n)*(a-b)^(2n-2)
=(a-b)^(2n+2n-2)
=(a-b)^(4n-2)