PCDVD數位科技討論區 - 瀏覽單個文章 - 30÷2(2+3)÷5是多少？　計算機答案不同

引用:

作者lowyield

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!

講了這種多，這篇其實已經把答案寫出來了，

An expression like 1/2x is interpreted as 1/(2x) by TI-82, but as (1/2)x by TI-83. While the first interpretation may be expected by some users, only the latter is in agreement with the standard rules stated above.

1/2x = 1/(2x) 是違反標準定義的。
當然這和很多數學、物理書上會有衝突，奶油酫大的例子就可見。
基本上我們可以認為書上寫得真的是錯誤的表示法；不然就是把 / 做成不同解釋。