等差中项证明等差数列等差中项证明等差数列222已知a,b,c依次成等差数列,求证:依次成等差数列.a,bc,b,ac,c,ab222要证三个数成等差数列,只需证明等式:a,bc,b,ac,c,ab2222222,即证成(b,ac),(a,bc),(c,ab),(b,ac)2(b,ac),(a,bc),(c,ab)立.?a,b,c成等差数列,d?b,a,c,b,d,c,a,2da,b,d,c,b,d(设其公差为),,2222?(a,bc),(c,ab),(a,ab),(c,bc),a(a,b),c(c,b)2,,ad,cd,d(c,a)...