max. value

[man111]

find greatest value of [tex](a-x)(b-y)(c-z)(ax+by+cz)[/tex]. where [tex]a,b,c[/tex] are positive and [tex](a-x),(b-y)[/tex] and [tex](c-z)[/tex] all are positive.

[mkmarinov]

There is no such value. There must be additional constraints on a,b,c or x,y,z.