1.4x^2n-1·y^2n+1分之0.8x^2n·y^2n-1

问题描述:

1.4x^2n-1·y^2n+1分之0.8x^2n·y^2n-1

=4/7*x^(2n-2n+1)y^(2n+1-2n+1)
=4xy^2/7