a^2/(bc)＝(b＋c)^2/(bc)＝b/c＋c/b＋2b^2/(ac)＝(a＋c)^2/(ac)＝a/c＋c/a＋2c^2/(ab)＝(b＋a)^2/(ab)＝b/a＋a/b＋2三式相加得：原式＝(b/c＋a/c)＋(c/b＋a/b)＋(c/a＋b/a)＋6＝(b＋a)/c＋(c＋a)/b＋(c＋b)/a＋6＝(...