The question is an illustration of arithmetic sequence.
<em>The number of conversation for 19 people is 171</em>
<u />
<u>(a) 9 people</u>
![Total = \frac{9 \times 8}{2}](https://tex.z-dn.net/?f=Total%20%3D%20%5Cfrac%7B9%20%5Ctimes%208%7D%7B2%7D)
9 represents the number of people
8 represents the number of conversation each person had
2 represents the number of people having a conversation at once (i.e 2 people at once)
<u>(b) 19 people</u>
We have:
![n = 19](https://tex.z-dn.net/?f=n%20%3D%2019)
The number of conversation is:
![Total = \frac{n \times (n -1)}{2}](https://tex.z-dn.net/?f=Total%20%3D%20%5Cfrac%7Bn%20%5Ctimes%20%28n%20-1%29%7D%7B2%7D)
So, we have:
![Total = \frac{19 \times (19 -1)}{2}](https://tex.z-dn.net/?f=Total%20%3D%20%5Cfrac%7B19%20%5Ctimes%20%2819%20-1%29%7D%7B2%7D)
![Total = \frac{19 \times 18}{2}](https://tex.z-dn.net/?f=Total%20%3D%20%5Cfrac%7B19%20%5Ctimes%2018%7D%7B2%7D)
![Total = 19 \times 9](https://tex.z-dn.net/?f=Total%20%3D%2019%20%5Ctimes%209)
![Total = 171](https://tex.z-dn.net/?f=Total%20%3D%20171)
Hence, the number of conversation for 19 people is 171
Read more about arithmetic sequence at:
brainly.com/question/18109692
Answer: y = 2x-7
Step-by-step explanation:
<span>Since 7 and 11 are both rational, the sum and difference are rational
</span><span>(p−7)=±11</span>
Since it is 900 + 2 + 0.6
the answer would be A
Answer:
16. B
17. B
18. B
19. B
20. B
I am not sure if they are all correct but I hope I helped you a tiny bit