It's better to be comprehensive. I've put all my remaining wealth on top of it,

It's better to be comprehensive. I've put all my remaining wealth on top of it,

1. Each copy number × copies = total number △ each copy number = total number △ copies number = each copy number 2, 1 multiple × multiples = several multiples △ 1 multiple = several multiples △ multiples = 1 multiple 3, speed × time = distance △ speed = time distance △ time = speed 4, unit price × quantity = total
There's plenty in the bookstore
Elementary mathematics formula book
There is a special chapter in the mathematics manual, chapter one!
Mathematical formula of high school key points
Common mathematical formula table table formula classification formula expression expression multiplication and the factorifactorifactoridecomposition (A2-B2 = (a + b) (b) (a-b) (a + b) (a + b) (a2-ab + B2) A3 (a + b) (a2-ab + B2) a3-b3 = (a + b) (a-b) (a-b) (A2 + AB + AB + B2) (A2 + AB + AB + B2) (a-b formula expression expression multiplication and factorifactorifactorifactorifactorifactorifactorifactorifactorifactoridecomposition (A2-B2) A2-B2 (a2-b (a + b) (a2-b) (a2-ab) (a2-ab + a2-ab + AB + AB + B2) A3 (a-b) (A2 + AB + AB + AB + AB + B2) the triangle inequality |a (a) a formula for the common mathematical formula for the common mathematical formula for the common mathematical formula for common mathematical formula in common mathematical formula table table table table table formula classification formula classification formula classification formula expression expression expression expression expression expression expression, the expression expression expression expression expression expression expression, the expression expression expression a ≤| a | one yuan
As long as the plural. My notes and confusion. Useful plural formula extracurricular please also issued
Sweat. It's 1 I / 1-I, and I ^ I ^ 3 Or something like that
Just know that I ^ 2 = - 1 and 1 / (a + bi) = (a-bi) / (a + bi) * (a-bi) = (a-bi) / (A2 + B2) where 2 is the power
Two primary school sixth grade math problem solving, urgent! Online, etc., to formula and explain
1. A cup of pure milk. Xiaoming drank a quarter of it for the first time, filled it with water, and then drank a quarter of it. What percentage of the pure milk did Xiaoming drink for the second time?
2. Chinese teachers count students' reading of world famous works. Half of the students in the class read one book, one fifth read two books, one eighth read three books and one tenth read four books. There are no more than 50 students in this class. How many students in the class have not read a famous book?
1. The proportion of milk consumed in the second time was 3 / 4, the proportion of pure milk consumed in the second time was (3 / 4) * (1 / 4) = 3 / 16;
2. Because it is impossible to have a decimal number, the whole class can be divided by 2, 5, 8 and 10, and the least common multiple of 2, 5, 8 and 10 is 40;
40-20-8-5-4 = 3, then 3 students in the class didn't read a famous book;
The general term of high school mathematics
Sum up the general term of high school sequence
Equal difference, equal ratio
Direct method: such as a (n + 1) = SQR (a (n))
There is another kind, such as a (n + 1) = 2A (n) + 1
A (n + 1) + 1 = 2 (a (n) + 1)
There are also multiplication, subtraction, period and so on
If you don't have any idea, write out the first few items. You can't guess first and then use mathematical induction to disprove
Finally, we must verify the first term with s (n + 1) - S (n)
There is a pile of walnuts on the beach. On the first day, the monkey ate 25% of the number of walnuts in the pile, threw away 4 and went to the sea. On the second day, the number of walnuts eaten plus 3 is 58% of the number of walnuts left in the first day, so the pile of walnuts is at least left___ One
Suppose there are x walnuts in total. The number of walnuts left in the first day: (1-25) x-4 = 35x-4, the number of walnuts eaten in the second day: (35x-4) × 58-3 = 38x-52-3 ∪ the last number left: 35x-4 - (38x-52-3) = 0.225x + 1.5 ∫ the last number left 0.225x + 1.5 must be an integer ∪ when x = 2
Let the sum of the first n terms of the sequence BN be SN. And BN = 2-2sn. The sequence an is an arithmetic sequence, A5 = 14. A7 = 20. Find the general term formula of the sequence BN. 2, if CN = an * BN (n = 1234 ）And TN is the sum of the first n terms of the sequence CN
1 B1 = 2-2s1 = 2-2b1 B1 = 2 / 3 BN = 2-2sn B (n-1) = 2-2s (n-1) the difference between the two formulas bn-b (n-1) = - 2bn BN = 1 / 3 * B (n-1) so BN = 2 * (the nth power of 1 / 3)
According to the condition, it is easy to get an = 3n-1 CN = 2 * (3n-1) * (n power of 1 / 3)
In addition, DN = cn-3 * C (n + 1) = - 6 * (power n of 1 / 3)
Tn-3*Tn=c1+c2+c3+…… +cn-3c1-3c2-c3-…… -3c3=（c1-3c2）+（c2-3c3）+…… +[C (n-1) - 3CN] + (cn-3c1) = [sum of the first n-1 of DN + (cn-3c1)] = - 2tn
The sum of the first n-1 terms of DN is - 2 * [1-1 / 3 (n-1 power)] / [1-1 / 3] = - 3 * [1-1 / 3 (n-1 power)]
-2tn = - 3 * [1-1 / 3 (n-1 power)] + 2 * (3n-1) * (1 / 3 N power) - 3 * 4 / 3 = - 7 + (9 + 6n-2) * (1 / 3 N power)
The solution is TN = 7 / 2 - (7 + 6N) * 1 / 2 * (the nth power of 1 / 3)
1. Starting from the starting point, plant a tree every 1 meter. If you hang three small wooden signs of "taking care of trees" on three trees, no matter how you hang them, the distance between at least two trees listed is even (in meters). Why?
2. How many different natural numbers can guarantee that the difference between at least two numbers is a multiple of 8?
3. Give 248 books to six (1) students. If at least one of them gets seven books, how many students are there in this class?
1. Left tree, middle tree, right tree if the distance from left tree to middle tree and from right tree to middle tree is even, it meets the requirements; if the distance from left tree to middle tree and from right tree to middle tree is odd, then the distance from left tree to right tree is even; so there must be an even number 2. Whether the natural number contains 0 or 0, 8 (012345678) do not contain 0
The general term formula of high school mathematics sequence
A1=1.5,An=____ 3nA(n-1)___ ,(n>=2,N+)
2A(n-1)+n-1
The general term formula of the sequence an
A1=1.5,An=____ 3nA(n-1)___ ,(n>=2,N+)
2A(n-1)+n-1
The general term formula of the sequence an
Let BN = n / an, then the above formula becomes: 3 * BN = 2 + B (n-1), where B1 = 2 / 3. The change is as follows: 3 (BN - 1) = B (n-1) - 1; so BN = 1 - 1 / (...)
I can't understand the meaning at all!!!! Write the expression more clearly
What do you mean, there should be a distance between words
One fourth of a box of apples was taken away for the first time, the remaining one fourth was taken away for the second time, and four apples were taken away for the third time, leaving 14
For the first time, 1 / 4 was taken, and for the second time (1-1 / 4) * 1 / 4 = 3 / 16
If we don't take 4 in the third time, there should be 14 + 4 = 18 left
The 18 corresponding scores should be 1-1 / 4-3 / 16 = 9 / 16
Then it turns out: 18 divided by 9 / 16 = 32
4\1+4\1+14+4
Have you learned practical problems?
Suppose there were X
First take 1 / 4 * x second take (x-1 / 4 * x) * 1 / 4
X-1/4*X-1/4*(X-1/4*X)=4+14
X=32
All as unit 1
Take 1 / 4 for the first time, 1-1 / 4 = 3 / 4 left
For the second time, (3 / 4) X1 / 4 = 3 / 16, and the remaining 3 / 4-3 / 16 = 9 / 16
All have: (14 + 4) / (9 / 16) = 32
There are x apples
Take 1 / 4x for the first time
Take 1 / 4 (x-1 / 4x) for the second time
1/4x+1/4(x-1/4x)+4=x-14
X = 32
Suppose there were x apples in this box
（X-1/4X）-1/4X-4=14
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It should be like this
Let X be the original number, then
(X-X*1/4)*1/4-4=14
It is reduced to x = 96
14+4=18
18/1/4=72
72/1/4=288
Solve the original x apples
1/4x + 1/4(1- 1/4)x + 4 + 14 =x
1/4x + 1/4(3/4)x + 18 =x
1/4x + 3/16x + 18 =x
x - 7/16x= 18
x=32