Author: Li Qing photo

Looking at the examination questions of senior high school entrance examination in recent years, the open question has aroused widespread concern, and the number of "application questions" that use mathematical knowledge to solve practical problems has increased. Rational number is the most basic and important content in algebra. In recent years, the examination of this part of knowledge mainly involves the following knowledge points. Take the 2005-2006 senior high school entrance examination questions as an example to explain as follows.

First, compare the sizes of numbers.

Example 1 (Changsha City, Hunan Province) The following table shows the monthly average temperature of four cities in China. Arrange them from high to low: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _.

Analysis: Because positive numbers are greater than negative numbers, and negative numbers with larger absolute values are smaller, the above data are arranged as follows: 2.4 C, -3.8 C, -4.6 C,-19.4c. 。

Example 2 (senior high school entrance examination in Weihai City, Shandong Province) If A+B < 0, A < 0, B > 0, the relationship between A, -A, B and -B is ().

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