In mathematics learning, people usually use the unknown x to represent things or numbers that they don't know beforehand. We are used to calling x an unknown number. However, adding a horizontal line to X usually specifies the average value of a number in the field of mathematics.
So adding a horizontal line to X and X are two different mathematical concepts. The mathematical meanings they express are different. That is, X represents a mathematical letter or unknown number, and the horizontal line on X represents the average value of a set of data.
Skills of clever calculation in mathematics
Mathematics is not like Chinese. Many questions can be answered with similar meanings. It requires the accuracy of calculation and cannot be wrong at all.
Extraction of common factor: this method actually uses the law of multiplication and distribution to extract the same factor, and the remaining items in the exam are often added and subtracted, and an integer will appear.
Split method: As the name implies, split method is to split a number into several numbers for the convenience of calculation. This requires mastering some "good friends", such as 2 and 5, 4 and 5, 2 and 2.5, 4 and 2.5, 8 and 1.25. Be careful not to change the size of the number when splitting.
Split term method: Fractional split term refers to splitting the terms in the fractional formula, so that the split terms are offset before and after. This split item calculation is called split item method. The common splitting method is to split a number into the sum or difference of two or more digital units.