## amorfide 3 years ago So it is time to ask a question of my own, i do not need an entire solution, just what the next step is

1. amorfide

|dw:1350055553188:dw|

2. amorfide

find the values of A and B

3. amorfide

i did the first step which gives me

4. amorfide

|dw:1350055629792:dw|

5. amorfide

not sure what to do next

6. amorfide

@Callisto can you help?

7. anonymous

@lgbasallote

8. anonymous

you tagged someone with an "i hate math" picture to a math question?

9. Callisto

Is it n(2n^2 + 3n -2) on the right side?

10. amorfide

yeah it is

11. Callisto

|dw:1350056495046:dw| Can you simplify it first?

12. amorfide

which side? left or right

13. Callisto

Both. There is a common factor.

14. amorfide

|dw:1350056560601:dw|

15. amorfide

that should be -2n on ther ight

16. amorfide

|dw:1350056701582:dw|

17. Callisto

Not really.$\frac{A}{6}n(n+1)(2n+1) +bn= n(n^2 + 3n -2)$$n[\frac{A}{6}(n+1)(2n+1)+b] = n(n^2 + 3n -2)$ Cancel the common factor. and expand the left side.

18. amorfide

you could change b to 6b/6 and take out a factor of 1/6 right?

19. Callisto

You can, of course. But there is a common factor on both sides that you can cancel, what is it?

20. amorfide

get rid of n on both sides? if not then i dont know waht the common factor is on both sides

21. Callisto

Yes! So, now, you get $\frac{A}{6}(n+1)(2n+1)+b = n^2 + 3n -2$So, expand the terms on the left. What do you get?

22. amorfide

now i shall multiply out

23. Callisto

Yes.

24. amorfide

|dw:1350057038246:dw|

25. amorfide

forgot my A's

26. amorfide

|dw:1350057107864:dw|

27. Callisto

Not really..$\frac{A}{6}(2n+1)(n+1) = \frac{A}{6}(2n^2+3n+1) = ...?$

28. amorfide

oh and it is 2n² on the right

29. amorfide

|dw:1350057219369:dw|

30. amorfide

so that means to get 2n² A has to be 6

31. Callisto

I'm sorry but I have to go now... Basically, you need to expand the first term on the left, combine the like terms and compare the coefficient of x^2, x and constant terms on both sides. Then you can find A and B. As for your expansion, sorry again that it is wrong.

32. amorfide

okay thank you! i shall work on this thank you for your help

33. Callisto

a has to be 6 is correct, I supposed :|

34. Callisto

Once you find a, then compare the constant term on both sides. You should be able to get b. Good luck :)

35. amorfide

b is-3

36. amorfide

thank you :D