The reciprocal sum of four consecutive natural numbers is nineteen twentieths, then the sum of the p

1) 1 2<19 20<1 Obviously, the first number cannot be 1 and the sum of the reciprocals is calculated with 2,3,4,5, and 1 2+1 3+1 4+1 5>1 is not true.

Then test with 3,4,5,6, 1 3+1 4+1 5+1 6=1 2+9 20=19 20

So these four numbers are 3, 4, 5, 6

The sum of the products of their two pairs is 45 + 44 + 30 = 119 choose 12) The number of apprentices processed is five-eleventh of the master, then the master does 35 (5 11) = 77 per hour.

The number of parts in this batch is 77 * 26 = 2 002.

1. The four numbers are , so the answer is 3*(4+5+6)+4*(5+6)+5*6=119

2. Set the processing time to x, the total number of parts y, then:

xy/26+35x=y

xy/26：35x=11：5

Solution: x=143 8, y=2002

There are a total of 2002 parts.

Idea 2: The apprentice processes the master's 5 11, then the apprentice's processing speed is the master's 5 11, and the master's processing speed is:

35 divided by 5 11 = 77 per hour, the total time spent by the master is 26 hours, then the total number of parts is:

77*26=2002.

Master processing per hour: 35 11 5 = 77 pcs.

Total parts: 77 26 = 2002 pcs.

The reciprocal sum of natural numbers is 19 20, which means that the common multiple of these four consecutive natural numbers is a multiple of 20.

1 2 1 3 1 4 1 5 1, not true.

1 3 1 4 1 5 1 6 19 years old 20 means that these 4 pure continuous natural numbers are 3, 4, 5, 6.

3+4+5+6 18, the reciprocal of the sum of the four numbers is 1 18. Staring.

Solve the eggplant and accompany the digging: set the first natural number.

is x, and the four natural numbers in a row are: x, x+1, x+2, x+3, then according to the title, 1 x+1 (x+1)+1 (x+2)+1 (x+3)=19 20, and the defibrillation nucleus gets x=3, so the reciprocal of the sum of the four numbers is 1 (3+4+5+6)=1 18.

The reciprocal sum of natural numbers is 19 20, and the common multiple of these four consecutive natural numbers is a multiple of 20.

1 2 1 3 1 4 1 5 1, not true.

Explain that these 4 consecutive natural numbers are 3, 4, 5, 6. Pick-up.

3+4+5+6 18, the reciprocal of the sum of the four numbers is 1 18

Because 1 is early and pure, 4 + 1 5 = 9 20

So it's 1 3+1 4+1 5+1 6=19 20, so these four natural numbers are 3, 4, 5, 6. The sum of Lu Pi is 3 + 4 + 5 + 6 = 18, and the reciprocal of the sum is 1 18

The reciprocal sum of 3, 4, 5, 6 is 19 to 20

So, the reciprocal of their sum is 1 18

Let the smaller one be X, and the larger one is X+1, so it will slip violently.

1/x + 1/(x+1) =19/90

After tidying up. 19 x 2 - 161 x - 90 = 019 x + 10) (x - 9) =0x = 9 (x = 10 19 rounded off).

Let's start with a number of xIf two numbers are continuous, then the other number is x+1 or x-1

1 x+1 (1+x)=9 20 (x+1+x) x(x+1)=9 20 to get this equation 9x -31x-20=0 to solve this equation x1=-9 5 x2=4 from the two natural numbers mentioned in the question, x1 does not meet the meaning of the topic. So x=4Another number x+1=5

It can also be solved with x-1, and the equation 9x -49x-20 = 0 is solved to get the equation x1 = 4 9 x2 = 5 from the two natural numbers mentioned in the question, x1 does not meet the meaning of the question, so x=5, and the other number x-1=4It can be deduced from the lack of gods and the stupidity of both kinds.

1/18。

Let these four consecutive natural numbers be a, a+1, a+2, a+3, and the meaning of the title is:

1/a+1/(a+1)+1/(a+2)+1/(a+3)=19/20

4 consecutive natural numbers should be 2 even numbers and 2 odd numbers. And in the product of two pairs, the odd number * odd number = the odd number.

19 20 = 1 2 + 9 20 = 1 2 + 4 20 + 5 20 = 1 2 + 1 5 + 1 4 discontinuous, then divided into 1 2:

Therefore, 19 20 = 1 3 + 1 4 + 1 5 + 1 6

So the four numbers are . Then the reciprocal of the sum of the four numbers is: 1 (3+4+5+6)=1 18.

The reciprocal is generally used to express the inverse of the multiplication of numbers, and is generally used in various number fields such as rational numbers, real numbers, complex numbers, and multiplication groups composed of congruence classes of modulo n.

Characteristics of the countdown.

1. A positive real number (except 1) plus its reciprocal must be greater than 2.

2. A negative real number (except -1) plus its reciprocal must be less than -2.

3. To find the reciprocal of an integer, you only need to regard the integer as a fraction with a denominator of 1, and then you can get it according to the method of finding the reciprocal of the fraction.

4. The reciprocal is the number itself is 1 and -1, the reciprocal of the positive number is positive, the reciprocal of the negative number is negative, and 0 has no reciprocal.

Find the average of the 4 reciprocals: 19 20 4=19 80 This 19 80 should be in the middle of the third and fourth numbers.

1 4>19 80>1 5 and backwards is between 4 and 5.

So these four numbers are

20=4×5

These two numbers are 4 and 5 respectively

Let these two natural numbers be x and (x+1) respectively.

1/x+1/（x+1）=9/20

Simplified to 9x 2-31x-20=0

i.e. (9x+5)(x-4)=0

Solution: x=-5 9 or x=4

Because it is a natural number, take x=4

So these 2 numbers are: 4 and 5.

Continuous natural number x, (x+1).

The sum of the reciprocals is 1 x+1 (x+1) = 9 20

Solve the equation x=4, x+1=5

4 and 5 Let the two natural numbers be x and y, then the reciprocal of these two natural numbers is 1 x and 1 y, respectively

There is the equation 1 x+1 y=9 20

x+y/xy=9/20

to get a system of equations. x+y=9

xy=20 gives x=4 y=5

4 and 5 have one number x and the other y. 1 x+1 y=9 20

4 and 5, because the reciprocal of 4 20 is 20, and 4 is about 5;

And 9 20 minus 4 20 is equal to 5 20, and the reciprocal of 5 20 is 20 5, which is about four.