x的2次方乘x的2n次方乘(y的n+1次方)的2次方
=x^2乘x^(2n)乘[y^(n+1)]^2
=x^(2n+2)乘y^(2n+2)
=(xy)^(2n+2)
x=-3,y=1/3
xy=-1
原式
=(-1)^(2n+2)
=1