In direct proportion: the change direction is the same, one quantity expands or contracts, and the other quantity also expands or contracts.

Inverse proportion: the change direction is opposite, one is obviously expanding (or shrinking) and the other is actually shrinking (or expanding).

2. The corresponding objects are different.

Proportion: Correspondence quotient, that is, the ratio (quotient) of every two correspondence numbers is fixed.

Inverse proportion: the corresponding product, and the corresponding product of every two numbers is certain.

3. Different relationships

Proportion: relationship: y/x=k (certain).

Inverse proportion: relation: xy=k (certain).

Extended data

Application of Positive Proportion and Inverse Proportion

Example: There is a book that Zhang Ming reads 10 pages every day and can finish it in 30 days. If you read 15 pages every day, how much can you finish reading in advance?

Analysis: first set it to "the actual x days can be read, and then subtract the actual days from the planned days." Two related quantities are "the number of pages read every day" and "the number of days read". The number of pages read every day is more than the important days, and the number of pages read every day is more than the important days, and the change direction is opposite. The number of pages read every day multiplied by the total number of pages read every day meets the three conditions of inverse ratio, that is, inverse ratio. Since it is inverse proportion, it is listed in the form of two equal products.

The number of pages planned to read every day × the number of planned days = the number of pages actually read every day × the number of days actually read.

Solution: Assuming it can be completed in X days, 15X= 10×30, x = 20,30-20 =10 (days).

Answer: It can be completed 10 days in advance.

Baidu Encyclopedia-Proportion and Inverse Proportion