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Question Number 120215 by benjo_mathlover last updated on 30/Oct/20

Prove that (((((a+b)(b+c)(c+a))/8) ))^(1/3)  ≥ (√((ab+bc+ca)/3))  for a,b,c > 0

Provethat(a+b)(b+c)(c+a)83ab+bc+ca3 fora,b,c>0

Answered by TANMAY PANACEA last updated on 30/Oct/20

((a+b)/2)≥(√(ab))   ((b+c)/2)≥(√(bc))  ((c+a)/2)≥(√(ac))  multiply them  (((a+b)(b+c)(c+a))/8)≥(√(a^2 b^2 c^ ))  (((a+b)(b+c)(c+a))/8)≥abc  [(((a+b)(b+c)(c+a))/8)]^(1/3) ≥(abc)^(1/3)   now(√((ab+bc+ac)/3)) ≥(√((ab×bc×ac)^(1/3) ))  (√((ab+bc+ac)/3)) ≥(a^2 b^2 c^2 )^(1/6)   (√((ab+bc+ac)/3)) ≥(abc)^(1/3)

a+b2ab b+c2bc c+a2ac multiplythem (a+b)(b+c)(c+a)8a2b2c (a+b)(b+c)(c+a)8abc [(a+b)(b+c)(c+a)8]13(abc)13 nowab+bc+ac3(ab×bc×ac)13 ab+bc+ac3(a2b2c2)16 ab+bc+ac3(abc)13

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