4． -17/32 的补码表示是______。 A.1.01111 B.1.01101 C.1.00001 D.0.11101

a，b，c成等差数列
=> a+c = 2b (1)
用反证法
if 1/a,1/b,1/c成等差数列
1/a + 1/c = 2/b
b = 2ac/(a+c) (2)
from (1) and (2)
4ac/(a+c) = a+c
(a+c)^2 =4ac
(a-c)^2 =0
a=c