## sleestak 2 years ago Given the following, x1=2 x2=-1 x3=-2 x4=5 x5=-4 x6=8 Find: 3 ∑ ( x subi - 1 ) 2 i=1

1. dpflan

I think I can handle this ;)

2. dpflan

$\sum_{i=1}^{i=3} (x_i - 1) ^2$

3. amistre64

the suspense is killing me :)

4. dpflan

You given 6 x_i values. The equation only wants you to consider x_i for (i=1 until i=3), that would be x1, x2, x3. The sigma is the symbol for sum. So the problem is to find the sum for the following events: plugging in each x_i subtracting 1 then squaring that. Hence you'll have 3 values that you then add to together to get the final value. $i=1, x_1 = 2, (2-1)^2 = 1$ $i=2, x_2 = -1, ((-1) -1)^2 = ...$ ... and so on

5. amistre64

could we expand the binomial and pick it apart sum for sum?

6. sleestak

OH! THANK YOU. DPFLAN, you are the best <3

7. dpflan

@amistre64 for sure, that would create even more suspense!

8. amistre64

the butler did it, im sure of it ....

9. dpflan

with the candlestick?

10. dpflan

@sleestak No problem, glad I could help!

11. amistre64

yes, with the candlestick lol ... get a clue

12. dpflan

@sleestak I imagine you may have some more problems that are similar to this that you need to work on, so good luck

13. sleestak

thanks. I'll tell you what I come up with

14. sleestak

9

15. sleestak

oh no. sorry one sec

16. sleestak

14. OK. I think I can do the other problem. THANKS :D

17. dpflan

x1 -> 1 x2 -> 4 x3 -> 9 SUM = 14, yeah, you're now an expert it seems

18. sleestak

you guys need to list finance as the next subject :D

19. dpflan
20. dpflan

It actually had/has a pretty strong following/support from a professor at NYU - http://pages.stern.nyu.edu/~adamodar/

21. dpflan

Math is the most active subject

22. sleestak

oh. excellent.

23. dpflan

So if your questions are mathematical, you'd probably be best served to ask them here because there is a greater mass of users in this group, so you're more likely get an answer.

24. sleestak

yeah totally. this is awesome! I am going to use this all the time in school

25. dpflan

awesome, tell your friends too! Also, I've the final question you asked about solved

26. dpflan

*got

27. sleestak

oh okay. let me post

28. sleestak

should I now 'close' this question?

29. dpflan

Yep