Question 7
Let $a,b,c,d$ satisfy $a+b+c+d=10$. Prove that $ab+bc+cd+da\ne50$.
VTMO 2026 - Grade 9 - Semifinal - SET 07 - Self-study Question 7
VTMO · VTMO 2026 - Grade 9 - Semifinal - SET 07 - Self-study
VTMO · VTMO 2026 - Grade 9 - Semifinal - SET 07 - Self-study