The ratio of class 1 to class 2 is 8:7. If 8 students from class 1 are transferred to class 2, the ratio of class 1 to class 2 is 4:5. How many students are there in each class?

The ratio of class 1 to class 2 is 8:7. If 8 students from class 1 are transferred to class 2, the ratio of class 1 to class 2 is 4:5. How many students are there in each class?

Originally, one class accounted for 8 of the two classes: (7 + 8) = 8 / 15
Later, one class accounted for 4 of the two classes: (4 + 5) = 4 / 9
So the total number is 8 (8 / 15-4 / 9) = 90
So the original class 90 × (8 / 15) = 48 people
Class 2 90-48 = 42
Originally, one class accounted for 8 of the two classes: (7 + 8) = 8 / 15
Later, one class accounted for 4 of the two classes: (4 + 5) = 4 / 9
So the total number is 8 (8 / 15-4 / 9) = 90 [people]
So the original class 90 × 8 / 15 = 48 [people]
Class 2 90-48 = 42
The definition of equal difference and equal ratio sequence, general term formula
Arithmetic sequence, if the difference between each item and its previous item of a sequence from the second item is equal to the same constant, this sequence is called arithmetic sequence, and this constant is called tolerance of arithmetic sequence, which is usually expressed by the letter D. the general formula of arithmetic sequence is: an = a1 + (n-1) d (1) the previous n terms and formula are: SN = Na1 + n (n
Arithmetic sequence: if a sequence starts from the second term, and the difference between each term and its previous term is equal to the same constant, the sequence is called arithmetic sequence, and the constant is called tolerance of arithmetic sequence, and the tolerance is usually expressed by the letter D. General formula: an = a1 + (n-1) d
Equal ratio sequence: if a sequence starts from the second term and the ratio of each term to its previous term is equal to the same constant, the sequence is called equal ratio sequence. This constant is called the common ratio of the equal ratio sequence, which is usually expressed by the letter Q (Q ≠ 0). General term formula: an = a1q ^ (n-1)
Arithmetic sequence: if a sequence starts from the second term, and the difference between each term and its previous term is equal to the same constant, the sequence is called arithmetic sequence, and the constant is called tolerance of arithmetic sequence, and the tolerance is usually expressed by the letter D. General formula: an = a1 + (n-1) d
Equal ratio sequence: if a sequence starts from the second term and the ratio of each term to its previous term is equal to the same constant, the sequence is called equal ratio sequence. This constant is called the common ratio of the equal ratio sequence, which is usually expressed by the letter Q (Q ≠ 0). General term formula: an = a1q ^ (n-1) [Note: if M + n = P + Q, then am.an=ap . AQ] because you didn't say that you want other formulas, column Sn =..., so don't publish. Put it away
4. If one tenth of the students in class 5 (1) is transferred to class 5 (2), the number of students in the two classes will be equal. The number of students in class 5 (2) is () of that in class 5 (1)
Set: the number of class 1 is X
The number of class 2 is y
Then: 1 / 10x + y = 9 / 10x
So y = 9 / 10x-1 / 10x = 8 / 10x = 4 / 5x
The original number of five (2) classes is four fifths of the number of five (1) classes
How to find the general term formula of equal difference and equal ratio sequence
There is an arithmetic sequence an + 1 = can-d with a number on both sides. What is the number?
What is the concept of accumulation, multiplication and division
The relationship between the nth term and the Nth-1 term is expressed, and then by using the superposition method, such as sequence 1,2,4,7,11, there is a [n] - a [n-1] = n, so a [n-1] - a [n-2] = n-1a [n-2] - a [n-3] = n-2... A [2] - a [1] = 1, all these formulas are added to get a [n-1] = n-1
The number of students in class one of grade six is 1.5 times that of class two. If six students are transferred from class one to class two, the two classes are equal. How many students are there in each class?
Class 2: 6 × 2 ÷ (1.5-1) = 24 people
Class 1: 24 × 1.5 = 36 persons
Class 2: (6 + 6) / (1.5-1) 24 (person)
Class 1: 24x1.5 = 36 (person)
How to distinguish the general term of equal difference and equal ratio sequence from piecewise function
For example, if you get the formula of the sum of the first n terms of a sequence, how can you quickly distinguish whether its general term formula is a piecewise function or a single function? You need both kinds of sequences. It's better to have examples and analysis,
Know the first n terms and Sn of the sequence
First, find the first term A1 = S1
Again, when n ≥ 2
an=Sn-S(n-1)
Find the general term, and then put A1 into the test to see if it meets the general term formula
If so, it is written as a single function
If not, it is written as a piecewise function
The arithmetic sequence is the same as the arithmetic sequence
The ratio of class 6 (1) to class 6 (2) is 8:7. If 8 students in class 6 (1) are transferred to class 6 (2), the ratio of class 6 (1) to class 6 (2) becomes 4:5?
A: there were 48 students in class one and 42 students in class two
High school mathematics triangle solution
Solution: tan3x * TaNx = 1
X=?
Detailed process principle is required
The answer is: Pie / 8
TAN3X * TANX=1
=> sin3x*sinx/cos3x*cosx=1
=> sin3x*sinx=cos3x*cosx
=> cos3x*cosx-sin3x*sinx=0
=> cos(3x+x)=0
=> 4x=π/2
=> x=π/8
Han, this thing only appears when 3x and X complement each other. So if x is limited to an acute angle, PI / 4 / 2 is pi / 8
The number of people in the first class is 5 / 6 of that in the second class. How many times is the number in the second class? What's the proportion of the number in the first class?
The number of people in the first class is 5 / 6 of that in the second class. How many times is the number in the second class? What's the proportion of the number in the first class?
Number of class one = (5 / 6) * number of class two
Then: the number of class 2 = (6 / 5) * the number of class 2 = 1.2 * the number of class 2
Number of people in class 1 / (number of people in class 1 + number of people in class 2)
=Number of people in one class / (number of people in one class + 1.2 * number of people in one class)
=Number of people in a class / [(1 + 1.2) * number of people in a class]
=1/(1+1.2)
=1/2.2
=10/22
=5/11
A: the number of the second class is 1.2 times that of the first class? The number of the first class accounts for 5 / 11 of the total number of the two classes
In △ ABC, the edge B opposite to acute angle B = 7, its circumcircle radius r = 733, and the area s of △ ABC = 103. Find the length of other two sides of △ ABC
∵ from the sine theorem, we can get SINB = B2R = 72.733 = 32, and B ∈ (0, π 2), ∵ B = π 3 S = 12, acsin B = 103, AC = 40 （1）… From the cosine theorem, we can get B2 = A2 + c2-2accosb, A2 + C2 AC = 49 （2）… A = 5C = 8, or a = 8C = 5 from (1) (2) So the other sides of the triangle are a = 5, C = 8, or a = 8, C = 5 The other two sides of △ ABC are 5 and 8