Do you know what the next number is? 50,39,17,6, 5, 16,What is the nth? What is the 2008th number

Let's get through first. a1-a2=11

a2-a3=12=11+1

a3-a4=13=11+2

a（n-1）-an=11+（n-2）

All kinds of left and right want to add:

a1-an=11×(n-1)+（1+n-2）（n-2）/2=11(n-1)+（n^2-3n+2）/2

So an=a1-11(n-1)+(n2-3n+2) 2=n2 2-25n 2+62

So the 2008th number is, let's bring it yourself.

There is a 28 between 39 and 17.

This is a series of equal differences.

an=a1+(n-1)d=50-11*(n-1) =61-11na2008=50+2007*(-11)=-22027 Upstairs is wrong, right? According to you, the first number is 55-11*1=39.

If you really don't have the number 28.

Then it should. a2008=50+39+17+（2008-3）*（11）=-21949

an=a3+(n-3)d=50-11n (n>=3) and a1=50 a2=39

Summary. It's a group.

There is a row of numbers 1, 3, 5, 1, 3, 5, 1, 3, 5, 5, 1, 3, 1, 3, 1, 3, 1, 1, 3, 1, 3, 1, 1, 3, 5, 1, 3, 5, 1, 3, 5, 1, 3, 5, 1, 3, 5, 1, 3, 5, 1, 3, 5,Then, the 26th number is (), and the sum of these 26 numbers is ().

It's a group. A group of 3. 26 3 = 8 groups. 2 pcs.

So the 26th is the second, and the number is 3

The number sum is 76

Thank you! I see. than the heart].

You can use a series of equal differences, with a tolerance of 2, the first term is 58, and the eleventh number is 58+2 (11-1)=78

First, determine the value: regardless of the symbol, the array is sequential, so the values of the 101st and 2008th numbers are 101 and 2008;

Then, determine the symbol: obviously, its law is "-", i.e. the law is repeated every three numbers, so, using our division method in the second grade of elementary school, divide the number to be speculated by 3, if.

Remainder. Yes 1; Add a "-" sign to the number, and if the remainder is 2, add a "-" sign to the number; If you can.

Divisible. i.e. there is no remainder), then add a "+" sign.

And 101 divided by 3 is the remainder is 2, so the 101st number is -101 and 2008 divided by 3 is 1, so the 2008th number is -2008

The law of this sequence is that when the number is divisible by 3, it is positive, and the rest of the cases are negative.

81 Subtract the latter from the former to obtain 3 6 8 11 14 16 and subtract the latter from the former one.

If it continues, it should be 3 2 3 3 2 3 cycle, and the next one is 16 + 3 = 19, so the next Senling spring term is 62 + 19 = 81

by y(1)=1

y(2)=6

y(3)=16

y(4)=31

y(5)=51, we can know:

y(n)=y(n-1)+5*(n-1)

Write it down and there is:

y(n-1)=y(n-2)+5*(n-2)……

y(2)=y(1)+5

Add all of the above equations (add the left and right sides respectively) to get :

y(n)+y(n-1)+…y(2)=y(n-1)+y(n-2)+…y(1)+5*(n-1)+5*(n-2)+…5

Offset the same parts on both sides to get:

y(n)=y(1)+5*n*(n-1)/2=1+5*n*(n-1)/2

Substituting n = 10, we get, y(10) = 226

Substituting n=100, we get, y(100)=24751, the nth digit is y(n)=1+5*n*(n-1) 2

It can be seen that this number is looped with 5 numbers 30561, which is 3056130561......30561……So the 40th digit is the 1 at the end of the 8th cycle, so the 41st digit should be the 3 at the beginning of the 9th cycle, so the sum of the first 41 digits is.

Solution: Investigate the set of numbers given by the landlord, and it is not difficult to find the following rules:

1. Positive and negative alternately, and the first number is positive;

2. Regardless of the symbol, the latter item is twice as large as the previous one.

Assuming that the nth digit is (an), then there is: (an)=[(-1) (n+1)]2 n

At n = 2010, there is:

a2010)=[(-1) 2011]2 2010=-2 2010, that's an astronomical amount!

I won't write it down, I'm afraid I can't write it here.

How many numbers are there in the numbers 7, 2, 0, 15, 20, 11, and 9? Which is the middle number?

The middle number is 9

There are 7 numbers, and the middle number is 9