1. First of all, any positive number preceded by a negative sign is equal to a negative number. 0 plus minus sign is not negative! On the number axis, all negative numbers are on the left of 0, and there is no smallest negative number. All negative numbers are less than natural numbers and less than zero (2). Secondly, China introduced the concept of negative number and the addition and subtraction of positive and negative numbers in Nine Chapters Arithmetic, and in some problems, the number sold is positive (because of income) and the number bought is negative (because of payment); More money is positive, less money is negative. In the calculation of grain, the addition is positive and the subtraction is negative. The words "positive" and "negative" have been used since then.

2. Finally, Steven uses positive and negative coefficients in the equation and accepts negative roots. Gerald (1595- 1629) equates negative numbers with positive numbers, and uses the minus sign "-"to represent negative numbers. In short, in the 16 and 17 centuries, although Europeans were exposed to negative numbers, the progress of accepting negative numbers was very slow, and negative numbers can be used to express various things such as temperature.