meaning
and
nature
Significance of (1) ratio
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Division of two numbers is also called the ratio of two numbers.
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":"is a comparative symbol, pronounced "than". The number before the comparison symbol is called the first item of comparison, and the number after the comparison symbol is called the last item of comparison.
Divide the last item by the former one.
income
Quotient, called
specific value
-
Compared with division, the ratio of the previous paragraph is equivalent to
bonus
The latter item is equivalent to
divisor
The ratio is equivalent to the quotient.
-
Usually use ratio
mark
You can also use it.
decimal
Represents, and sometimes it may be an integer.
-
The last term of the ratio cannot be zero.
According to fraction and division
relationship
As we all know, the ratio of the previous paragraph is equivalent to
molecule
The latter item is equivalent to
denominator
, the ratio is equivalent to the fractional value.
(2) the nature of the ratio
-
The first term and the second term of a ratio are multiplied or divided by the same number (except 0) at the same time, and the ratio is unchanged, which is called the basic property of the ratio.
(3) Find the ratio and simplify the ratio
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The method of finding the ratio: divide the former term of the ratio by the latter term, and the result is that a numerical value can be an integer, a decimal or a fraction.
-
According to the basic properties of the ratio, the ratio can be reduced to the simplest integer ratio. Its result must be the simplest ratio, that is, the first term and the last term are prime numbers.
(4) scale
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Distance on the map: actual distance = scale
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Find a scale; Know the distance and scale on the map and find the actual distance; Find the distance on the map by knowing the actual distance and scale.
-
line segment
Scale: The notes attached to the drawings are marked as
figure
The line segment of is used to indicate the actual distance from the ground.
(5) Proportional distribution
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In agricultural production and daily life, it is often necessary to allocate a quantity according to a certain proportion. This distribution method is usually called proportional distribution.
-
Method: First, find out each one.
part
Take a fraction of the total, and then find out what a fraction of the total is.
2
Significance and nature of proportion
( 1)
The meaning of proportion
-
Represents two equal ratios.
formula
This is called proportion.
-
The four numbers that make up a proportion are called proportional terms.
-
The two items at both ends are called external items, and the two items in the middle are called internal items.
(2) the nature of proportion
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In proportion, the product of two outer terms is equal to the product of two inner terms. This is the basic nature of the so-called proportion.
(3) solution ratio
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According to the basic nature of proportion, if any three terms in the proportion are known, another unknown term in this numerical proportion can be found.
Finding the unknown term in the proportion is called the solution ratio.
three
Positive proportion and inverse proportion
(1) is a proportional quantity.
-
Two related quantities, one quantity changes and the other quantity changes, if these two quantities
many
The ratio (i.e. quotient) of the corresponding two numbers is definite, and these two quantities are called proportional quantities, and their relationship is called.
direct ratio
(2) inversely proportional quantity
-
Two related quantities, one variable and the other variable. If the product of the corresponding two numbers in these two quantities is certain, these two quantities are called inverse proportional quantities, and their relationship is called
inverse relation