ab/a+b=1 则 (a+b)/ab = 1bc/b+c=1/2 则 (b+c)/bc = 2ac/a+c=1/3 则(a+c)/ac = 3所以 1/a + 1/b = 1 ; 1/b + 1/c = 2; 1/a + 1/c = 3;所以 1/a + 1/b + 1/c = 3所以 (bc+ ac + ab)/abc = 3所以 abc / (ab+bc+ca) = 1...