x(m-x)(m-y)-m(x-m)9y-m)

问题描述:

x(m-x)(m-y)-m(x-m)9y-m)

x(m-x)(m-y)-m(x-m)(y-m)
=x(m-x)(m-y)-m(m-x)(m-y)
=(m-x)(m-y)(x-m)
=-(m-x)^2(m-y)