這個符號點解!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

正數和負數
例如：4的平方根可以是2 或-2，答案便可寫成 ±2
(2x2=4；-2x-2=4)

It represents a RANGE of values based on a given number. Eg., 100 +/- 10 gives a range of values from (100-10) to (100+10), i.e., 90 to 110. You use this symbol whenever you want to specify a range of values with same difference in each direction of a based number.

問題:±這個符號點解

答案:正負。
例如:±3cm(即可有3cm相差)

正或負

通常用係計error 度會見到

左右, 大約的意思.