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anonymous

  • one year ago

Which of the following represents the zeros of f(x) = x3 − 14x2 + 61x − 84?

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  1. anonymous
    • one year ago
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    @lyn

  2. anonymous
    • one year ago
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    @LynFran

  3. anonymous
    • one year ago
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    @LynFran

  4. anonymous
    • one year ago
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    @welshfella

  5. welshfella
    • one year ago
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    try some of the factors of 84 f(4) = 0 so (x -4) is a factor

  6. anonymous
    • one year ago
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    ok

  7. anonymous
    • one year ago
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    3 a factor?

  8. welshfella
    • one year ago
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    now as -84 is the last term and x - 4 is a factor you could see if the factors of 21 could be zeros try finding f(3) and f(7)

  9. anonymous
    • one year ago
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    so7,4, and 3

  10. welshfella
    • one year ago
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    yes 3 is a factor

  11. welshfella
    • one year ago
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    3 is a zero i meant

  12. anonymous
    • one year ago
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    yes, may u help on another?

  13. welshfella
    • one year ago
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    well is f(7) = 0 ?

  14. welshfella
    • one year ago
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    you need to check that f(3) and f(7) = 0

  15. anonymous
    • one year ago
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    ok, is 3 a factor?

  16. anonymous
    • one year ago
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    or -3

  17. welshfella
    • one year ago
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    i checked f(3) it is = 0 so 3 is a zero

  18. anonymous
    • one year ago
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    and i checked 7 and it is a zero

  19. welshfella
    • one year ago
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    3 is not a factor (x -3) will be a factor

  20. anonymous
    • one year ago
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    ok

  21. anonymous
    • one year ago
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    may you help on a nother

  22. welshfella
    • one year ago
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    f(7) also = 0 yes 4,3 and 7 are correct

  23. anonymous
    • one year ago
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    Which of the following is a polynomial with roots 3, 5i, and −5i?

  24. welshfella
    • one year ago
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    ok

  25. welshfella
    • one year ago
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    if x = 3 then one factor will be (x - 3) and the other 2 will be (x + 5i) and (x - 5i) what do you get when you multiply x + 5i and x - 5i ?

  26. anonymous
    • one year ago
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    x^2-25i

  27. anonymous
    • one year ago
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    @welshfella

  28. welshfella
    • one year ago
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    not quite (x - 5i)(x + 5i) = x^2 + 5xi - 5xi -5i*5i = x^2 - 25i^2 = x^2 - 25* -1 = x^2 + 25 remember that i^2 = -1

  29. anonymous
    • one year ago
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    ahh ok then what?

  30. welshfella
    • one year ago
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    so to get your polynomial you must multiply:- ( x - 3)(x^2 + 25)

  31. anonymous
    • one year ago
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    then we multiply by (X-3) for the answer right?

  32. anonymous
    • one year ago
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    yeah that right

  33. anonymous
    • one year ago
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    @welshfella what is our final answer?

  34. welshfella
    • one year ago
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    well do the multiplication (x - 3)(x^2 + 25) = x^3 + 25x can you continue?

  35. welshfella
    • one year ago
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    you need to multiply the second parenthesis by -3

  36. anonymous
    • one year ago
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    ok

  37. anonymous
    • one year ago
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    -3x^2-75

  38. anonymous
    • one year ago
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    f(x) = x^3 − 3x^2 + 15x − 75 IS THAT THE ANSWER?

  39. anonymous
    • one year ago
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    @welshfella

  40. welshfella
    • one year ago
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    its 25x not 15x

  41. anonymous
    • one year ago
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    sry i mistyped

  42. anonymous
    • one year ago
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    thanks dude

  43. welshfella
    • one year ago
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    yw

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