sandeep what did u do after u got one of the has to be less than -1??? can u explain a bit here is my proof let x,y,z be the roots of a cubic P(b)=b^{3}+ub-v u=xy+yz+zx all it's roots lie within [-2,1] thus the roots of P'(b)=0 alpha,eta also lie within [-2,1] so alpha,=+sqrt{-u/3}<=1 thus u+3 >=0 or 6>=-2u=0^{2}-2u=x^{2}+y^{2}+x^{2}
Moderation Team
![[Post New]](/templates/default/images/icon_minipost_new.gif){kind=icon}
![[Up]](/templates/default/images/icon_up.gif "[Up]"){kind=icon}
106
