Test Prep 1 - DS 037

[lisayang83]

--------r---------s--------t-------
Is 0 halfway between r+s

1. s is to the right of zero
2. distance between t and r equals the distance between t and -s

Ans. C

I chose b...[/u]

[dibert8]

(1) s > 0
(2) t - r = t - (-s) => -r = s, or r = s = 0

(1) & (2) => -r = s > 0

[dianechiu]

條件(2)是否可能出現|t-r|=|t-(-s)|=>t-r=t-(-s)或t-r=-s-t?
為何t-r=-s-t不需要考慮?
還有s是否有<0的可能?
一直想不透,想請教大家 謝謝

[dibert8]

(2) 有兩種情形:
--(r)----(s)---(t)--(0)-----(-s)-- 或 --(r)-----(0)-----(s)---(t)--