3 / 14 plus 3 / 14 times 13 (simple formula)

3 / 14 plus 3 / 14 times 13 (simple formula)

Original formula = 3 / 14 + (3 / 14) * 13
=(3/14)(1+13)
=(3/14)*14
=3;

Primary school test questions (those who can calculate simply should be calculated simply): 2 / 5 / (3 / 4 + 2 / 5), {1 - (1 / 4 + 3 / 8)} / 1 / 4, 2 / 13 / 15 / 26 * 5 / 8

2/5/(3/4+2/5)=2/5/23/20=2/5*20/23=8/23{1-(1/4+3/8)}/1/4=(1-1/4-3/8)/1/4=(3/4-3/8)/1/4=3/4*4-3/8*4=3-3/2=3/22/13/15/26*5/8=2/13*26/15*5/8=4/15*5/8=1/6 keyima

Calculation: - 1 / 10 * 11-1 / 11 * 12 - -1/19*20
Calculation: 1
- ——— - ——— - …… - ———
10×11 11×12 19×20

：-1/10*11-1/11*12-…… -1/19*20
=-(1/10*11+1/11*12+...+1/19*20)
=-(1/10-1/11+1/11-1/12+...+1/19-1/20)
=-(1/10-1/20)
=-1/20

How to calculate 1 / 10 * 11 + 1 / 11 * 12 + 1 / 12 * 13 +. + 1 / 19 * 20 simply

Since 1 / 10 * 11 = 1 / 10-1 / 111 / 11 * 12 = 1 / 11-1 / 121 / 12 * 13 = 1 / 12-1 / 13, the original formula = = (1 / 10-1 / 11) + (1 / 11-1 / 12) + (1 / 12-1 / 13) +. + (1 / 19-1 / 20) = 1 / 10-1 / 11 + 1 / 11-1 / 12 + 1 / 12-1 / 13 +. + 1 / 19-1 / 20 = 1 / 10-1 / 20 = 1 / 20

Put the natural numbers 1, 2, 3 98 and 99 are divided into five groups. If the average of each group is equal, what is the sum of the five averages?

1,2,3…… The sum of 98 and 99 is (1 + 99) + (2 + 98) + +(49 + 51) + 50 = 100 * 49 + 50 = 49504950 divided by 5 to get 950. The average of each group is equal to the sum of the number of reorganization divided by their number. Suppose that the sum of each group is x, y, Z, a, B respectively

In 99 continuous natural numbers, the largest number is 25.5 times of the smallest number, so the average of these 99 natural numbers is______ ．

The largest number is larger than the smallest number: 99-1 = 98, the smallest number is: 98 △ 25.5-1 = 4, the largest number is: 4 + 98 = 102, the average number is: (4 + 102) △ 2 = 53; so the answer is: 53

Put the natural numbers 1, 2, 3 99 is divided into three groups. If the average of each group is exactly equal, then the product of the three means is______ ．

Let the average number of each group be x, then 33x + 33x + 33x = 1 + 2 + 3 + +99, that is, 99x = (1 + 99) × 99 △ 299x = 99 × 50, x = 50. So the product of the three averages is 503 = 125000. So fill in 125000

The average of data 101, 100, 99, a and B is 100, and the variance is 2
Such as the title

(a+b)=200,
a^2-b^2=2,
That is, (a + b) (a-b) = 2,
That is, A-B = 1 / 200,
a=4001/200,b=3999/200;
The answer is strange. Who and whose is the variance

There are three natural numbers, the largest one is 6 larger than the smallest one, and the other is just the average of the two numbers, and their chance is 42560. What are the three numbers
You do it by short division,

Let these three numbers be a, B and C, where a is the largest and C is the smallest （1）A+C＝2B…… （2）A*B*C＝42560…… (3) From (1) a = 6 + C is substituted into (2) 6 + C + C = 2B, i.e. B = C + 3, a = 6 + C and B = C + 3 are substituted into (3) respectively to get: (6 + C) * (c + 3) * C = 42560, and the solution is: C

There are three continuous natural numbers. The smallest one is a and the largest one is (). The average of these three numbers is ()

There are three continuous natural numbers, the smallest one is a, the largest one is (a + 2), and the average of these three numbers is (a + 1)