(y-x)m次幂(x-y)5次幂(y-x)n次幂(x-y)3次幂
=(y-x)m次幂(y-x)5次幂(y-x)n次幂(y-x)3次幂
=(y-x)的(m+5+n+3)次幂
=(y-x)的(m+n+8)次幂