What is proportion?
Proportion, in mathematics, refers to the proportion of the number of parts in the population, which is used to reflect the composition or structure of the population. Two related quantities, one of which changes and the other changes with it. Two expressions with equal ratios are called ratios, such as 3: 6 = 9: 18.
① Two formulas with equal ratios are called ratios, such as 3: 4 = 9: 12 and 7: 9 = 2 1: 27.
In 3: 4 = 9: 12, 3 and 12 are called external proportional terms, and 4 and 9 are called internal proportional terms.
There are four items in the proportion, namely two internal items and two external items; In 7: 9 = 2 1: 27, 7 and 27 are called external proportional terms, and 9 and 2 1 are called internal proportional terms.
There are four items in the proportion, namely two internal items and two external items.
For example, both teachers and students have met the requirements.
For example, among the goods sold, domestic products account for a relatively large proportion.
(4) After the proportion is written as a fraction, the denominator on the left and the numerator on the right are internal terms, and the numerator on the left and the denominator on the right are external terms.
⑤ In a proportion, the product of two external terms is equal to the product of two internal terms, which is called the basic property of proportion.
⑥ Similarities and differences between proportion and inverse proportion.