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anonymous

  • one year ago

Need Help, medal + fan: Which are true of the function f(x) = 49 (1/7)x? Check all that apply. A:The domain is the set of all real numbers. B:The range is the set of all real numbers. C:The domain is x > 0. D:The range is y > 0. E:As x increases by 1, each y-value is one-seventh of the previous y-value. F:The initial value for the function is

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  1. UsukiDoll
    • one year ago
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    \[\large f(x)=49(\frac{1}{7})^x \] is this the function for the question? or \[\large f(x)=49(\frac{1}{7})x \]

  2. anonymous
    • one year ago
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    first one

  3. UsukiDoll
    • one year ago
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    ok... well our function doesn't have denominators so there are no restrictions.

  4. UsukiDoll
    • one year ago
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    the domain is at the x-axis the range is at the y-axis

  5. UsukiDoll
    • one year ago
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    we need to graph this function t-t

  6. anonymous
    • one year ago
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    Okay..

  7. butterflydreamer
    • one year ago
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    note: you can also re-write your function as: |dw:1436850224394:dw|

  8. UsukiDoll
    • one year ago
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    we need x = 1,2,3... and so on.. for \[\large f(x)=49(\frac{1}{7})^x \]

  9. UsukiDoll
    • one year ago
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    we can use desmos. easier XD

  10. anonymous
    • one year ago
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    Ohh okay you have to graph to see it..

  11. UsukiDoll
    • one year ago
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  12. anonymous
    • one year ago
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    I wasn't graphing it, so that is why it was really difficult to see

  13. UsukiDoll
    • one year ago
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    yeah... sometimes questions are easier when you graph but since this function is too screwed up (I don't feel like doing it manually lol) we use desmos which graphs it for us

  14. anonymous
    • one year ago
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    So from the graph, I already concluded what some of the answers could be, but still not sure if I am right, could you check to see? I will screenshot it

  15. UsukiDoll
    • one year ago
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    sure

  16. anonymous
    • one year ago
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  17. UsukiDoll
    • one year ago
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    The first 2 is indeed all real numbers as I mentioned earlier we don't have a function that's like a fraction ex. \[f(x) =\frac{1}{x-2} \] which means we can't have x be 2

  18. anonymous
    • one year ago
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    Right, so A and B are correct..

  19. UsukiDoll
    • one year ago
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    yes... hmm interesting on the last one.. I mean that would work if x = 1, but I could've sworn that initial value would mean that x = 0 .

  20. UsukiDoll
    • one year ago
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    like.. if x = 1 \[\large f(1)=49(\frac{1}{7})^1\] \[\large f(1)=49(\frac{1}{7})\] \[\large f(1)=(\frac{49}{7})=7\] If x = 0 \[\large f(0)=49(\frac{1}{7})^0\] (due to the zero exponent rule.. anything to the 0 results in 1 ) \[\large f(0)=49(1) = 49\]

  21. anonymous
    • one year ago
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    Okay, we are getting somewhere haha. So we already know A and B are correct, anything else I am missing, or something I marked incorrectly?

  22. UsukiDoll
    • one year ago
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    \[\large f(2)=49(\frac{1}{7})^2\] \[\large f(2)=49(\frac{1}{49})\] \[\large f(2)=1\]

  23. UsukiDoll
    • one year ago
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    when my x is increasing I have f(0) = 49 f(1) = 7 f(2) = 1

  24. anonymous
    • one year ago
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    So Y is decreasing..

  25. UsukiDoll
    • one year ago
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    I'm confused at that wording though... for the second to the last .. but yeah my y is going down.. fast.

  26. UsukiDoll
    • one year ago
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    x y 0 49 1 7 2 1

  27. UsukiDoll
    • one year ago
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    and it claims that when x is increasing the previous y is 1/7 th of the previous y value.

  28. UsukiDoll
    • one year ago
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    ?!

  29. anonymous
    • one year ago
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    Right...? That is not true though. so we can eliminate that one

  30. UsukiDoll
    • one year ago
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    I don't think so it's like 49 ./ 7 =7 7/7 = 1 Then again maybe if I calculate f(3) \[\large f(3)=49(\frac{1}{7})^3 \] \[\large f(3)=(\frac{49}{343}) \] \[\large f(3)=(\frac{1}{7}) \]

  31. UsukiDoll
    • one year ago
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    let's try f(4) maybe that question is talking about that? \[\large f(4)=49(\frac{1}{7})^4\]

  32. anonymous
    • one year ago
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    Hey I'm sorry I am running really short on time, So lets just sum it up. What do you think are the answers?

  33. UsukiDoll
    • one year ago
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    \[\large f(4)=\frac{49}{2401}\]

  34. UsukiDoll
    • one year ago
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    \[f(4) = \frac{1}{49}\]

  35. UsukiDoll
    • one year ago
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    first two are fine last one is when x = 0 , so it's not 7

  36. anonymous
    • one year ago
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    Okay, and that is all?

  37. UsukiDoll
    • one year ago
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    ugh trying to think to those 3 ...

  38. UsukiDoll
    • one year ago
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    second to the last one is confusing... x.x

  39. anonymous
    • one year ago
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    We'll just say no to that one...SO now we are left with C and D.

  40. UsukiDoll
    • one year ago
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    if it's all reals then that would have the domain and range at >0

  41. UsukiDoll
    • one year ago
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    I see it well on the range though. when y > 0

  42. UsukiDoll
    • one year ago
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    on the graph

  43. UsukiDoll
    • one year ago
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    but the domain is smoosh... like it's just on the line

  44. UsukiDoll
    • one year ago
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    so first two are fine domain is smoosh it's just 0 flat range is greater than 0 no idea - split on that one it's not 7 because x = 0 for initial conditions.

  45. UsukiDoll
    • one year ago
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    I think after x = 3 the previous is 1/7 due to 1/7 (1/7)(1/7) (1/7)(1/7)(1/7)

  46. anonymous
    • one year ago
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    Okay thank you

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