1, different formulas
The direct ratio is (x/y = k (certain)) and the inverse ratio is (xy = k (certain)). In direct proportion: A is big, B is big, and AB is in direct proportion. Inverse ratio: The greater A, the smaller B, and the inverse ratio of AB. The direct ratio of two quantities means that the "quotient of these two quantities" is a fixed value, and the inverse ratio of the two quantities means that the "product of these two quantities" is a fixed value.
2. Different laws
The positive ratio is that one number is reduced several times, another number is also reduced several times, one number is expanded several times, and the other number is also expanded several times; Inverse proportion means that one number shrinks several times, another number expands several times, and one number expands and another number shrinks several times. (It's not a question of getting bigger and smaller. For example, if -2 is enlarged three times, it will be -6, but its value will be smaller, not enlarged).
The relationship between positive and negative proportions:
I. Similarities between positive proportion and inverse proportion:
1, the relationship between things has two variables, one is quantitative.
2. Among these two variables, when one variable changes, the other variable will also change.
3. The product or quotient of the corresponding two variables is certain.
Second, the conversion between positive proportion and inverse proportion:
When the value of inverse proportion x (the value of independent variable) is also converted into its reciprocal, it is converted from inverse proportion to positive proportion; When the value of x in a positive proportion (the value of independent variable) is transformed into its reciprocal, it is transformed from a positive proportion to an inverse proportion.
The proportional image is on the light passing through the origin. It develops from the intersection of the abscissa and ordinate of the statistical table, along the diagonal line from the lower left corner to the upper right corner, and extends out of the table. In the sense of direct ratio, it can extend downward, so it is considered as a straight line.