之前有人貼wiki
http://en.wikipedia.org/wiki/Order_of_operations
裏面有寫到
Similarly, care must be exercised when using the slash ('/') symbol. The string of characters "1/2x" is interpreted by the above conventions as (1/2)x. The contrary interpretation should be written explicitly as 1/(2x). Again, the use of brackets will clarify the meaning and should be used if there is any chance of misinterpretation.
我想這也是為何casio & TI 會把原本的1/2X等於1/(2X)修改為1/2X等於(1/2)X的原因吧?應該就是這種問題造成太多人困擾了!
我手上沒數學書可以查,不過GOOGLE 1/2X, SIN(1/2X), 1/2PI之類的方程式...應該滿多類似問題的!