If {an} is an arithmetic sequence, A1 = 2, d = 3, what is the sum of the first 10 terms of the sequence?

If {an} is an arithmetic sequence, A1 = 2, d = 3, what is the sum of the first 10 terms of the sequence?

a10=a1+9d=29
So S10 = (a1 + A10) * 10 / 2 = 155

There is a sequence: 4.10.16.22,..., find the 50th term

This is an arithmetic sequence
d=a2-a1=10-4=6
an=a1+(n-1)d=4+6(n-1)=6n-2
So find the 50th term and substitute 50 into an to get 6 × 50-2 = 298
So item 50 is 298

7 10 16 22 () sequence 4 options 28 32 34 45

2*3+1=7
3*3+1=10
5*3+1=16
7*3+1=22
Because 2.3.5.7. Is the first few prime numbers, the next one should be 11
11*3+1=34

① 2/3,8/9,3/4,2,( ) ② 19/13,1,13/19,10/22,( ) ③ 3/7,1/2,7/13,9/16,( )

① Wrong title, 2 / 3, 8 / 9, 4 / 3, 2, ()!
Turn into
6/9,8/9,12/9,18/9,
The denominator is 9,
Molecule 6,8,12,18,26, phase difference 2,4,6,8
()=26/9
②19/13,16/16,13/19,10/22,7/25
Three for each molecule
Add three to each denominator
③ The second number can be changed to 5 / 10
So above the fraction line are 3, 5, 7, 9, 11
Below the score line should be 7, 10, 13, 16, 19
So the answer is 11 / 19

The law of sequence 0,1,3,8,21

Add the first two numbers to get the last one, divide 0 and 1

2,0,3,5,8, what are the rules of sequence

It can be found that the interval between each number is 2,3, for example, 2 is added between 2 and 0, 3 is added between 0 and 3, 2 is added between 3 and 5, and 3 is added between 5 and 8, so 2,3 is the interval order between each number. The next is 8 + 2 = 10

There is a sequence rule, which is: 1, 2, 3, 5, 8, 13, 21... What is the tenth number of the request?
I don't know what the law is. Are there any experts willing to give directions?

The latter number is the sum of the first two numbers (in bolajian sequence);

1 4 15 64 (325)

The law between 0 14 15 64 (325) and 0 14 15 64 (325) is as follows
(0)×1+1=(1)
(1)×2+2=(4)
(4)×3+3=(15)
(15)×4+4=(64)
(64)×5+5=(325)
That is, the law is that the first number multiplied by its number of terms plus its number of terms equals the next number

Are the numbers 0, 1, 4, 15, 64, () regular? What should be in brackets

0、1、4、15、64、（325）
0 1 4 15 64
0*1+1 1*2+2 4*3+3 15*4+4
64*5+5=325

Find the rule and fill in the number 0.1.4.15.64

（0+1）*1； （1+1）*2=4; （4+1）*3=15； （15+1）*4=64； （64+1）*5=325；