1. If two variables are directly proportional, when one variable increases by a certain multiple, the other variable will also increase by a certain multiple. For example, if the time for a person to run a lap is directly proportional to his speed, the faster his speed, the shorter his time for completing a lap. Proportionality can be expressed by the following formula: y = kx, where k is a proportional constant.
2. If two variables are inversely proportional, when one variable increases by a certain multiple, the other variable will also decrease by a certain multiple. For example, if the speed of a car is inversely proportional to its driving time, the speed will decrease as the driving time increases. Inverse proportion can be expressed by the following formula: y = k/x, where k is an inverse proportion constant.
3. If there is no obvious correlation between two variables, then they can be considered as irrelevant. For example, a person's height and weight have nothing to do, because there is no fixed proportion and relationship between them.
4. To judge the relationship between two variables, we can observe the trend and relationship between them according to the changes of two variables over time or conditions. Then we can use mathematical methods to judge whether these two variables are directly proportional, inversely proportional or irrelevant. If there is a proportional relationship, the relationship between two variables can be expressed by a proportional coefficient, for example, y = k/x or y = k/x.
5. Proportional constant refers to the proportional coefficient between two variables, which can be determined by known conditions. For example, if there is a positive proportional relationship between two variables, the coordinates of any point can be determined by experiment or observation, and the proportional constant can be calculated by using the coordinates of this point. If the inverse relationship between two variables is known, the coordinates of any point can be determined by experiment or observation, and the proportional constant can be calculated by substituting the inverse ratio formula.
Positive-negative ratio
The positive-negative ratio refers to the relative relationship between one or more logarithms, in which the increase or decrease of one number is directly proportional to the increase or decrease of another number. Positive and negative proportional expansion refers to further expansion and application on the basis of this proportional relationship.
In the field of art design, positive and negative proportion is a widely used design skill, especially in composition and typesetting. For example, using positive proportion can help designers to better control the size and scaling of pictures, so as to achieve a more unified and harmonious effect. In addition, inverse proportion can also be used in concrete design, for example, the font size of inverse proportion can enhance the emphasis of some information.
At the same time, in natural science, the positive-negative ratio also has important applications. For example, scales in music are formed by the law of positive proportion, and some phenomena and laws in astronomy, chemistry and biology will also use the related concepts of positive and negative proportion when expressing and explaining them.