若a,b,c,d均为正数。求证[(b/a )+(d/c)] [(c/d)+(a/d)] ≥4
∵左≥2√(bd/ac)×2√(ac/bd)=4=右
∴左≥右
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若a,b,c,d均为正数。求证[(b/a )+(d/c)] [(c/d)+(a/d)] ≥4
∵左≥2√(bd/ac)×2√(ac/bd)=4=右
∴左≥右