213. In an electric circuit, two resistors with resistances x
and y are connected in parallel. In this case, if r is the
combined resistance of these two resistors, then the
reciprocal of r is equal to the sum of the reciprocals of
x and y. What is r in terms of x and y ?
(A) xy
(B) x + y
(C) 1/x + y
(D)xy/x + y
(E)x + y/xy
答案D。reciprocal of r is equal to the sum of the reciprocals of x and y ，个人认为此句应当理解为1/r=1/x+y；但OG似乎理解为1/r=1/x+1/y。求教各位牛牛，这句话到底表达啥意思？作者: melissa_gao 时间: 2011-11-6 06:32
他问得是the sum of the reciprocals of x,y是两个先倒再加，而你说的那个是 the reciprocals of the sum of x,y~~我是这么理解的~~非nn一枚~~作者: cyvivi 时间: 2011-11-8 06:39
