The first line: 1, the second line: - 2,3, the third line: - 4,5, - 6, the fourth line: 7, - 8,9, - 10.. what is the fifth line in the tenth line? The first line: 1, the second line: - 2,3, the third line: - 4,5, - 6, the fourth line: 7, - 8,9, - 10.. what is the fifth line in the tenth line?

The first line: 1, the second line: - 2,3, the third line: - 4,5, - 6, the fourth line: 7, - 8,9, - 10.. what is the fifth line in the tenth line? The first line: 1, the second line: - 2,3, the third line: - 4,5, - 6, the fourth line: 7, - 8,9, - 10.. what is the fifth line in the tenth line?

The first number in the tenth row is - [(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9) / 2 + 1] = - 46, and the fifth number is - (46 + 4) = - 50

The number of columns - 1,2, - 3,4, - 5,6, - 7 is arranged in the following form: the first row - 1, the second row 2 - 3 4, the third row - 56 - 7, 8 - 9, the tenth row, the second on the left is?

The first number in line 12 is 0.5 * 12 * 11 + 1 = 67, and the fifth number in line 15 is 0.5 * 15 * 14 + 5 = 110

The number in a column is arranged according to the following rule: 1, 2, 3, 2, 3, 4, 3, 4, 5, 5, 5, 5, 6, 7, starting from the first number on the left, the top 100

The sum of the first 100 numbers is (1 + 2 + 3) + (2 + 3 + 4) + (3 + 4 + 5) +. + [n + (n + 1) + (n + 2)] = 6 + 9 + 12 +. + 3 (n + 1) = n [6 + 3 (n + 1)] / 2 = 3N (n + 3) / 2, which is exactly the 99g33 = 33, and the 100th number is 34. Therefore, the sum of the first 100 numbers is 3 * 33 * 36 / 2 + 34 = 1782 + 34 = 1816

Observe the following column numbers 1, - 2, - 3,4, - 5,6. As shown in the figure, - 2011 is the () number on the left of line () as shown in the figure? -1 2 -3 4 -5 6 -7 8 -9 10 -11 12 -13 14 -15 16

By observing the structure of the sequence, we can see that:
1. The odd part is negative and the even part is positive
2. Each row has an odd number and 2 increments,
3. The number one is the number. The sign is different
So:
1 number in the first line
The second line has (1 + 2 * 1) = 3 numbers
The third line has (1 + 2 * 2) = 5 numbers
.
There are [1 + 2 * (n-1)] in the nth row
So there are 1 + 3 + 5 +... + [1 + 2 * (n-1)]
Let Sn = 1 + 3 + 5 +... + [1 + 2 * (n-1)]
Then Sn = [1 + 2 * (n-1)] + [1 + 2 * (n-2)] +... + 5 + 3 + 1 (reverse addition)
The sum is: 2Sn = [1 + 1 + 2 * (n-1)] + [3 + 1 + 2 * (n-2)] +... + [1 + 2 * (n-1) + 1]
=2n + 2n +... + 2n (n items in total)
So Sn = n * n
Because 44 * 44 = 1936
45*45=2025
So 2011 is on line 45
2011-1936=75
So it's item 75 from left to right
It is concluded that: - 2011 is the (75) on the left of line (45)
(SN is the formula of the sum of the first n items of the arithmetic progression learned by senior high school. The summation method adopted in this answer is the method of the sum of the first n items of the arithmetic sequence in the high school textbook --- the method of adding in reverse order.)

A series of numbers 2, 5, 9, 14 The 19th number in this string is () A. 207 B. 209 C. 211 D. 213

2+3+4+5+… +19+20，
=（1+20）×（20÷2）-1，
=21×10-1，
=209；
A: the 19th number is 209
Therefore, B

The arrangement of a string of numbers is: the first number is 20, and from the second number, each number is 8 less than the previous number (1) What's the tenth number? (2) What's the nth number? (3) The number is - 60

（1）20-8×（10-1）=-52，
The 10th number is - 52;
(2) The nth number = 20-8 (n-1);
(3) 20-8 (n-1) = - 60, n = 11,
The 11th number is - 60

There is a column of numbers; 2, 5, 8, 11, 14. According to the law, what is the 1995 number?

2+（N-1）*3
N=1995
5984

There is a column of numbers, arranged as follows: 1, - 2,4, - 8,16, - 32. Among them, the sum of three consecutive numbers is - 96. What are the three digits

-32 64 -128

The number of columns arranged regularly; what is the nth digit of 2-6-18-54-162?

2*3↑（n-1）

There is a column of numbers 2, 5, 8, 11... According to this arrangement, what is the 19th number

2+(19-1)x3=56