Question 5
(FRG 1) IMO1 Let $x,y,z$ be nonnegative real numbers with $x+y+z=1$. Show that
$$0\le xy+yz+zx-2xyz\le\frac7{27}.$$
$$0\le xy+yz+zx-2xyz\le\frac7{27}.$$
IMO 1984 - Shortlisted Problems Question 5
IMO Shortlist · IMO 1984 - Shortlisted Problems