1, difference method: compare the sizes of two numbers A and B. You can first calculate the difference between A and B, and then judge the sizes of A and B according to the positive and negative difference. If a-b >; 0, then a & gtb；; If a-b
2. Doing business: Comparing the sizes of two numbers, you can first calculate the ratio of a/b, and then judge the sizes of A and B according to the positive and negative ratio. If a/b >; 1, then a & gtb；; If a/b
3. Absolute value method: To compare the sizes of two numbers A and B, you can first remove the absolute value sign, convert A and B into positive numbers, and then compare them. This method applies to both positive and negative numbers, but you need to pay extra attention to the sign of the number.
4. Square difference method: Comparing the sizes of two numbers A and B, you can first calculate the square of (a-b), and then judge the sizes of A and B according to the sign of the square. What if (a-b)? & gt0, then a & gtb；; What if (a-b)? & lt0, and then
Matters needing attention in comparing sizes in mathematics:
1. Determine the number or quantity to be compared, which can generally be compared according to the numerical value given by the topic or the interval range given by the topic.
2. The comparison of series or inequalities needs to be carried out in a certain order, such as from small to large or from large to small.
3. For some complicated series or inequalities, appropriate deformation or simplification is needed for better comparison.
4. In the process of comparing sizes, we need to pay attention to the characteristics of positive and negative values and zero values in order to compare and judge better.