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jessifosho

  • one year ago

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

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  1. myininaya
    • one year ago
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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)

  2. jessifosho
    • one year ago
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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

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

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

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

  6. jessifosho
    • one year ago
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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. :(((

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

  8. myininaya
    • one year ago
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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)

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

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

  11. jessifosho
    • one year ago
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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?

  12. myininaya
    • one year ago
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    No...

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

  14. myininaya
    • one year ago
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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

  15. myininaya
    • one year ago
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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.

  16. jessifosho
    • one year ago
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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

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

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

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

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

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

  22. myininaya
    • one year ago
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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

  23. jessifosho
    • one year ago
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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

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

  25. myininaya
    • one year ago
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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,....

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

  27. jessifosho
    • one year ago
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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.

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

  29. jessifosho
    • one year ago
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    Oh?

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

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

  32. myininaya
    • one year ago
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    Yep that is right

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

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

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

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

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

  38. myininaya
    • one year ago
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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.

  39. jessifosho
    • one year ago
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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?

  40. myininaya
    • one year ago
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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

  41. jessifosho
    • one year ago
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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?

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

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

  44. jessifosho
    • one year ago
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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:

  45. jessifosho
    • one year ago
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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)

  46. myininaya
    • one year ago
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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.

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

  48. jessifosho
    • one year ago
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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.

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

  50. jessifosho
    • one year ago
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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:

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

  52. myininaya
    • one year ago
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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

  53. jessifosho
    • one year ago
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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)

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

  55. jessifosho
    • one year ago
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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

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

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

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

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

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

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