常用方法公式法等代换法、换元法、反证法、三角法、比较法、分析法、综合baaccbabcabc:,cba)3(ba1abba:,Rb,a)2(ba)ab()ba(:,0b,0a)1(1222222222121212212求证设求证设求证设例)bac)(acb)(cba(abc)2(cbacabbcaabc)1(:,0c,b,a2求证设例abccaabcc)2(abc)1(:bac2,0c,b,a3222求证设例abc)1(bac2,0b,a2求证,bac2,0c:证明)1(2bac)2(ab2ba0b,aabc:)2()1(得、由成立abc2b1ba1aba1ba:4求证例)3)(2)(1.(D)3)(1.(C)2)(1(.B)1(.A)()Rb,a)(1ba(2ba)3()Rb,a(bababa)2()Rx(x23x)1(.1223223552其中正确的不等式是已知下列不等式练习:D__________________________322107.2的大小关系是与322107分析法22333baba:,Rb,a.3求证设1ab:),b(f)a(f,ba0,xlg)x(f.4求证且实数设)cabcab(4)cba(:,ABCc,b,a.52求证的三边之长为设2x1x33:.62求证2qp:.2qp,Rq,p.733求证且已知