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a,b,c,d in AP and a,h,k,d in GP --> bc ≥ hk - [Canada 1979]

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September 29, 2011
arithmetic sequence

Problem Statement

Given: (i) aa, b>0b > 0; (ii) aa, A1A_1, A2A_2, bb is an arithmetic progression; (iii) aa, G1G_1, G2G_2, bb is a geometric progression. Show that A1A2G1G2.A_1 A_2 \ge G_1 G_2.