Beibei uses matchsticks to make an octagonal graph. Eight matchsticks are used for one graph, 15 for two, and how many matchsticks are used for 100 octagons, How many matchsticks do n octagons use?

700 for 100 octagons and (8n-n) for N. of course, one octagon is not included

As shown in the figure, in the triangle ABC, D is the point on the edge AC, and ab = ad

Find the rule of triangle
There is a triangle arranged as
one
2 2
3 3 3
4 4 4 4
.
Find out where the number of 2010 is?

Suppose that in row n:
2010=4020>62*63
n=63
2010-62*63/2=57
The number (63) in 2010 is 57 in row 63

Find the rules and draw the figures

Circle is 1, 2 is triangle, so it is a circle in triangle

If we know that the number of items of the arithmetic sequence {an} is even, and the tolerance d = 1, and the sum of odd numbers is 44, and the sum of even numbers is 33, then the middle items and the number of items of this sequence are equal
If we know that the number of items of the arithmetic sequence {an} is even, and the tolerance d = 1, and the sum of odd items is 44, and the sum of even items is 33, then the middle items and the number of items of this sequence are equal
Is it the wrong title

There should be something wrong with the title
If the number of terms is even, then an even term corresponds to an odd term, and the difference is 1, but the sum of even term and - odd term is less than 0, which is contradictory

It is known that the number of terms of the arithmetic sequence an is odd, A1 = 1, the sum of odd terms of an is 175, and the sum of even terms of an is 150

Let the total number of items be n. from the meaning of the title, it can be seen that the odd number items have (n + 1) / 2 items, the even number items are (n-1) / 2 items, which can be obtained from the formula an = a1 + (n-1) d, the end item of the odd number column is 1 + [(n + 1) / 2-1] 2D, and the end item of the even number column is 1 + D + [(n-1) / 2-1] 2D

Given that the tolerance of the arithmetic sequence {an} is 2, the number of items is even, the sum of all odd items is 15, and the sum of all even items is 25, then the sequence {an} is

The number of items is even, so the number of even items is the same as that of odd items
Sum of even items - sum of odd items = 10 = 5 * 2 (tolerance)
5 even and 5 odd
The fifth is 15 / 5 = 3, and the sixth is 25 / 5 = 5
an=2n-7（1≤n≤10）

The number of items of the arithmetic sequence {an} is even, the sum of odd items is 44, the sum of even items is 86, and the tolerance is 2
Please hurry up, brothers

When the number of terms is 2n (n ∈ n +), s-even-s-odd = nd
Let's just take in 2n = 42, so there are 42 terms

In the arithmetic sequence {an}, if A1 > 0, S3 = S11, then what is n when Sn takes the maximum value?

Let the first term be A1 and the tolerance be d
{s3=(a1+a1+2d)/2*3=3*(a1+d)
{s11=(a1+a1+10d)/2*11=11*(a1+5d)
∴3a1+3d=11a1+55d
-8a1=52d
a1=-(13/2)d
∵a1＞0
∴d＜0
A negative number from item 8
When n = 7, take the maximum value

In the arithmetic sequence {an}, A1 = 13, S3 = S11

Let the tolerance be d,
Because S3 = S11
So 3 * 13 + 3 * (3-1) / 2 D = 11 * 13 + 11 * (11-1) / 2 d
39+3d=143+55d
d=-2
sn=13n+n(n-1)/2 *(-2)
=-n^2+14n
=-(n-7)^2+49
So when n = 7, Sn max = 49

Beibei uses matchsticks to make an octagonal graph. Eight matchsticks are used for one graph, 15 for two, and how many matchsticks are used for 100 octagons, How many matchsticks do n octagons use?