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jessifosho Group Title

Generate the first 5 terms of this sequence: f(1) = 0 and f(2) = 1, f(n) = f(n - 1) + f(n - 2), for n > 2. A. 0, -1, 1, 0, 2 B. 0, 1, 1, 2, 3 C. 0, 1, 2, 2, 3 D. 0, 1, 1, 2, 2 Please helppp! Thanks! <3

  • one year ago
  • one year ago

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  1. myininaya Group Title
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    f(n)=f(n-1)+f(n-2) Try replacing n with 3 like so f(3)=f(3-1)+f(3-2) f(3)=f(2)+f(1) You know what f(2) equals and you know what f(1) equals f(2)=1 and f(1)=0 Replace f(2) and f(1) with 1 and 0 respectively and then add those values to get f(3)

    • one year ago
  2. jessifosho Group Title
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    Um... f(3) = f(1) + f(0) So, f(3) equals 1? How do I get all those other numbers in the choices? :o

    • one year ago
  3. myininaya Group Title
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    you keep going up with n

    • one year ago
  4. myininaya Group Title
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    find f(4) using the same f(n)=f(n-1)+f(n-2) formula

    • one year ago
  5. myininaya Group Title
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    then do f(5) and so on...

    • one year ago
  6. jessifosho Group Title
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    ... But what //is// f(5)? Idk I've been doing this for like an hour and the lesson is horrible at describing it. :(((

    • one year ago
  7. jessifosho Group Title
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    And I'm not supposed to find f(5), I think... I'm supposed to find 5 terms or something.

    • one year ago
  8. myininaya Group Title
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    f(1), f(2),f(3),f(4),f(5) are the numbers in your sequence. f(1) and f(2) are given we just found f(3) given f(n)=f(n-1)+f(n-2) then we do the same for f(4) and f(5) Evaluate: f(4)=f(4-1)+f(4-2) and f(5)=f(5-1)+f(5-2)

    • one year ago
  9. myininaya Group Title
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    You must do f(4) before you do f(5) though

    • one year ago
  10. myininaya Group Title
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    Since to evaluate f(5), you will need to know f(4) and f(3)

    • one year ago
  11. jessifosho Group Title
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    f(4) = f(4-1) + f(4-2) f(4) = f(3) + f(2) f(4) = 5? _________ f(5) = f(5-1) + f(5-2) f(5) = f(4) + f(3) f(5) = 7? Is this correct?

    • one year ago
  12. myininaya Group Title
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    No...

    • one year ago
  13. jessifosho Group Title
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    ...? I don't understand. D:

    • one year ago
  14. myininaya Group Title
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    So f(1)=0 f(2)=1 f(3)=f(3-1)+f(3-2) =f(2) +f(1) But we are given that f(2) is 1 and f(1) is 0 So we replace f(2) with 1 and we replace f(1) with 0 like so =1 +0 =1 So we just concluded as we concluded earlier that f(3) is 1 not 3

    • one year ago
  15. myininaya Group Title
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    Now to find f(4) You use the same formula f(n)=f(n-1)+f(n-2) this is the same formula we used to evaluate f(3) We will use this formula over and over until we are done finding numbers in the sequence (which this sequence goes on forever) So anyways f(4) Replace n with 4 f(4)=f(4-1)+f(4-2) =f(3) +f(2) Recall we just found f(3) and f(2) was given to us.

    • one year ago
  16. jessifosho Group Title
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    ... I am so confused. Okay so the formula comes out to ... f(4) = f(1) + f(1)? ??? ?? So the answer is 2? Does that make the answer to the entire problem C? :S

    • one year ago
  17. myininaya Group Title
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    well f(3) is just one not f(1) and f(2) is just one not f(1)

    • one year ago
  18. myininaya Group Title
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    f(1) is not equal to f(2)

    • one year ago
  19. myininaya Group Title
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    but 1 is equal to f(2)

    • one year ago
  20. myininaya Group Title
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    but yes 1+1 is equal to 2

    • one year ago
  21. jessifosho Group Title
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    But in the problem... it says " f(2) = 1"?

    • one year ago
  22. myininaya Group Title
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    yes f(2) =1 but f(2) does not equal f(1) f(1) is 0 0 is never 1 so f(2) is never f(1) because they hold different values

    • one year ago
  23. jessifosho Group Title
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    Oh. I thought they were the same lol w/e. So is the answer C or do I have to waste my time farther into the problem?? :o

    • one year ago
  24. myininaya Group Title
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    I'm pretty sure that is not what we got...

    • one year ago
  25. myininaya Group Title
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    the first five terms are f(1),f(2),f(3),f(4),f(5) we have that f(1)=0, f(2)=1, f(3)=1, f(4)=2,....

    • one year ago
  26. jessifosho Group Title
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    Ohhh or it could be B or D. I know it isn't A...

    • one year ago
  27. jessifosho Group Title
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    Ugh so I have to do more. x_x Math sucks omfg. Okay so lemme figure out the 5 term thingy.

    • one year ago
  28. myininaya Group Title
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    You don't have to do more.

    • one year ago
  29. jessifosho Group Title
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    Oh?

    • one year ago
  30. myininaya Group Title
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    You just aren't realizing what we got for the first 4 numbers I guess

    • one year ago
  31. jessifosho Group Title
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    Well two choices have "0, 1, 1, 2" as the first four numbers...

    • one year ago
  32. myininaya Group Title
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    Yep that is right

    • one year ago
  33. myininaya Group Title
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    0,1,1,2,....

    • one year ago
  34. myininaya Group Title
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    So yeah we do have go one more because b and d both begin with that (sorry didn't realize)

    • one year ago
  35. myininaya Group Title
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    I leave finding f(5) to you

    • one year ago
  36. jessifosho Group Title
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    Whats the equation thingy??

    • one year ago
  37. myininaya Group Title
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    f(n)=f(n-1)+f(n-2) this is the same one we have been using

    • one year ago
  38. myininaya Group Title
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    If we want to find f(5) and we are given f(n)=f(n-1)+f(n-2) then in order for f(n) and f(5) to be the same n would have to be 5. So replace all the n's you see in f(n)=f(n-1)+f(n-2) with 5.

    • one year ago
  39. jessifosho Group Title
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    f(5)=f(5-1)+f(5-2) f(5) = 4 + 3 f(5) = 2 + 1 f(5) = 3 So it's "B," right?

    • one year ago
  40. myininaya Group Title
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    You mean that f(5-1) is equal f(4) and that f(5-2) is equal to f(3) You only performed the inside operation You haven't even used f So You should have f(5)=f(5-1)+f(5-2) =f(4) + f(3) because 5-1 is 4 and 5-2 is 3 =2 + 1 because f(4) is 2 and f(3) is 1 =3 The answer is right Just the work was a little off. But yes now we can say what the answer is

    • one year ago
  41. jessifosho Group Title
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    Yeah I don't need to show my work. Math is stupid so as long as I have the right answer, I'll pass. :) Hey, can you help me check the answer I found on the first part of a different question? Just so I know I'm on the right path to the correct answer?

    • one year ago
  42. myininaya Group Title
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    Math isn't stupid.

    • one year ago
  43. myininaya Group Title
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    Math is in everything.

    • one year ago
  44. jessifosho Group Title
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    Lol I'm more of a calculator type of girl, myself. I'm a writer so it's not as important to me (unless someday a girl behind the cash register at the grocery store makes me solve a complicated equation about substitutions for x or whatever (with work shown!) LOL) So yeah, anyways, can you help just check my answer for the first part of this thing? I need to get this work done so I don't fail World History. D:

    • one year ago
  45. jessifosho Group Title
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    (I'm homeschooled so my douchy World History teacher is going to call me in like 15 minutes and ask a bunch of questions I'll end up blundering on x_x. Next semester I'm going back to brick and mortar before I flunk World History and Algebra completely. lol)

    • one year ago
  46. myininaya Group Title
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    Well, I would have to say it would help you and I have if you had a more positive attitude about math.

    • one year ago
  47. myininaya Group Title
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    And any of your future math tutors.

    • one year ago
  48. jessifosho Group Title
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    Yeah any positivity on the subject more along the lines of me looking forward to the bright horizon: the time that I'm allowed to stop taking math classes. Lol. I guess what motivates me is the "It'll be over soon~" idea like soldiers on the battlefield or somebody starving to death in the wilderness. I'd like to get it done and not have math bring down my 4.0 GPA. x_x I've always sucked at it, no matter how hard I try, and I don't like the subject in general (In my opinion, it's a bit impractical. Nobody I've ever met that isn't in a field like architecture or something has ever meticulously plotted graph points. And the only fractions I've ever found to be actually necessary in real life are 1/2, 1/3, and 1/4, basically.) I guess I'll never be a mathematician. *shrugs* Oh well. Lol.

    • one year ago
  49. myininaya Group Title
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    Go ahead and post your other problem.

    • one year ago
  50. jessifosho Group Title
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    Okay. :) "Find f(5) for this sequence: f(1) = 2 and f(2) = 5 f(n) = f(1) + f(2) + f(n - 1) n > 2. f(5) = ______ " This is the problem. I made this equation: f(3) = f(1) + f(2) + f(3 - 1) So, with this, I ended up making: f(3) = 2 + 5 + f(3 - 1) The "f(3 - 1)" part is confusing me. I don't know what to do with this section as I try to evaluate the terms. D:

    • one year ago
  51. myininaya Group Title
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    3-1 equals 2

    • one year ago
  52. myininaya Group Title
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    so what is f(3-1) equal to? f(3-1) is equal to f(2) and f(2) is given to you in the problem

    • one year ago
  53. jessifosho Group Title
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    Oooh! Okay, I didn't think about it that way. f(3) = 2 + 5 + 5 f(3) = 12 Is this correct? (My original answer wasn't at all; I got 9 somehow. Lol)

    • one year ago
  54. myininaya Group Title
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    that is right! good job!

    • one year ago
  55. jessifosho Group Title
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    Okay! :)) Now one last question; how do I translate that into finding the 4th term? f(4) = f(1) + f(2) + f(4 - 1) f(4) = 2 + 5 + 12 Does it look like this to solve it? :3

    • one year ago
  56. myininaya Group Title
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    Yep! That is great. I think you are getting it.

    • one year ago
  57. jessifosho Group Title
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    Okay! Thanks for all your help! :D

    • one year ago
  58. myininaya Group Title
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    I'm really happy that you are happy that you did it. :) Now I must go. Good luck on everything.

    • one year ago
  59. myininaya Group Title
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    I gave you a medal for understanding by the way. :)

    • one year ago
  60. jessifosho Group Title
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    Great, thanks! :))

    • one year ago
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