1. The terms of a sequence are denoted by

2.

3. so it is clear that the first columns add each time by one, and the second column add by 2, then by 4, by 6, by 8 and so on.
4. consider only the second column and how we get the terms, which we will call

:


5.
So
![u_{n}=(n+1)(1+2{1+2+3+....(n-1)}) =(n+1)(1+2 [(n-1)n/2]) = (n+1)(1+(n-1)n) =(n+1)( n^{2}-n+1 ) ](https://tex.z-dn.net/?f=u_%7Bn%7D%3D%28n%2B1%29%281%2B2%7B1%2B2%2B3%2B....%28n-1%29%7D%29%0A%20%20%20%20%20%20%20%20%0A%20%20%20%20%20%20%20%20%20%3D%28n%2B1%29%281%2B2%20%5B%28n-1%29n%2F2%5D%29%0A%0A%20%20%20%20%20%20%20%20%20%3D%20%28n%2B1%29%281%2B%28n-1%29n%29%0A%20%20%20%20%20%20%20%0A%20%20%20%20%20%20%20%20%20%3D%28n%2B1%29%28%20n%5E%7B2%7D-n%2B1%20%29%0A%20%20%20%20%20%20%20%20%20)
6. We can check:

7. Remark: Gauss addition formula: 1+2+3+....+n=n(n+1)/2
Answer:
0.92
Step-by-step explanation:
The highest rainfall was 1.25
The lowest rainfall was 0.33
1.25-0.33=0.92
Concave pentagon
Explanation: pentagons have 5 sides
180 because it goes up by 6's every time so the answer is D.
Answer:
i think 65 but if not then it is D impossible
Step-by-step explanation:
hope that helps
and that i wasn't to late