The number of columns arranged according to the regulations is 2, 3, 10, 15, 26 and 35. What is the seventh number? If the answer is right, a reward will be offered!

Is the title wrong? The order should be 2, 3, 10, 15, 26, 35, 50;
Or 1 / 2, 1 / 3, 1 / 10, 1 / 15, 1 / 26, 1 / 35

We know a group of numbers - 1 in 2, 4 in 17, 5 in - 26, and so on______ ? There is only one formula, expressed by the power of n

((-1)^n)*n/(n^2+1)

2,-3/5,10/7,-15/17,26/31,-35/65,…… Then what is the nth number of this column? (expressed in an algebraic expression containing n)

Do not say in detail, the computer will run out of power, give you an idea, you are sorting
Let's look at the denominator, 2 = 2 / 1, odd digit number. The denominator is the nth power of 2-1, and the denominator is the nth power + 1 of 2
Let's look at the number of odd digits. The numerator is the square of N + 1, and the denominator of even number is n squared-1
Then the odd number is negative, and the even number is positive
Let's talk about it. When n = 2K + 1, n = 2k-1, it's OK,

A column number - 2 / 2,3 / 5, - 4 / 10,5 / 17, what is the nth number

(- 1) ^ n times (n + 1) / (n ^ 2 + 2n + 2)

Fill in: 1 2，2 5，3 10，4 17，______ ，6 37．

4+1
17+9＝5
26，
So the answer is: 5
26．

Negative half two fifths negative four tenths What's the nth number

The nth power of (- 1) * n / (n * n + 1)

There is a column of numbers: half, minus two fifths, three tenths, minus four seventeen. What is the tenth number

Add: wrong, it should be 10 of 101

There is a column of numbers minus half, two fifths, three tenths, four seventeen... The seventh number is

The rules are as follows:
Symbol: negative, positive and negative
Molecular: 1,2,3,4
Denominator: 2 = 1 ^ 2 + 1,
5=2^2+1,
10=3^2+1,
17=4^2+1.
So the seventh number is
-7/50.

Observe the following column numbers: 1 / 2, - 1 / 6, 1 / 12, - 1 / 20,. Please find out the rule of arrangement and fill in the blanks according to this rule. (1) what is the ninth number? What is the 14th number?; (2) if n is an integer greater than 1, write the nth number according to the above arrangement rule

The ninth number is 1 / (9 * 10), and the fourteenth is - 1 / (14 * 15)
The law is as follows:
When n is odd: the nth number = 1 / [n * (n + 1)]
When n is even: the nth number = - 1 / [n * (n + 1)]

Look at the following columns: half, minus six, twelve, minus twenty... Find the pattern and answer the following question (1) The ninth number is (), and the fourteenth is () (2) If n is an integer greater than 1, write the nth number according to the above rule

(1) The ninth number is (1 / 90) and the fourteenth is (- 1 / 210)
(2) If n is an integer greater than 1, write the nth number according to the above rule
Firstly, it is determined that the odd number term is positive and the even term is negative (- 1) ^ (n + 1)
Second, look at the rules of denominators
1*2、2*3、3*4、4*5、.、n（n+1）
So the nth number is: (- 1) ^ (n + 1) / N (n + 1)

The number of columns arranged according to the regulations is 2, 3, 10, 15, 26 and 35. What is the seventh number? If the answer is right, a reward will be offered!