MathDB
Three variable inequality for juniors

Source: Tuymaada 2016. Junior League/P4

July 22, 2016
inequalities

Problem Statement

Non-negative numbers aa, bb, cc satisfy a2+b2+c23a^2+b^2+c^2\geq 3. Prove the inequality (a+b+c)39(ab+bc+ca). (a+b+c)^3\geq 9(ab+bc+ca).