"Add or subtract" means positive or negative, and symbols can be used to represent the positive or negative of rational numbers, or to add and subtract logarithms in four operations. Symbol is not a single concept in middle school physics. Some symbols are equivalent to rational numbers in mathematics, while others are used to express the nature and direction of physical quantities. The situation is more complicated. There are three specific situations:

The mathematical symbols "1" and ""indicate positive and negative, such as "1":+1and-1.

2. For addition and subtraction, it means 3 1: it means 3+1= 4,3-1= 2.

3. Indicates an error: for example, 10 1: indicates that this number is between 10- 1 and1+1,that is, 9 and 1 1.

Extended data

input method

1, wps symbol input

Take WPS2003 as an example: click "insert", "symbol" and "Latin-1", then find the symbol, click and enter it into the document.

2. Enter symbols in word.

Menu bar, insert, special symbols, mathematical symbols, just the last one in the first row.

3. You can adjust the input method to the intelligent ABC state, and then enter V 1 to turn the page and search.

4. Press ALT and press 0 177 to release ALT, which is "+".

5. Input "Fu Zheng" with sogou input method or Baidu input method.

Baidu Encyclopedia-plus sign or minus sign