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burhan101

x intercept for this function

  • 10 months ago
  • 10 months ago

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  1. burhan101
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    \[\huge y=x^3-9x^2+15x+4\]

    • 10 months ago
  2. burhan101
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    this is unfactorable?

    • 10 months ago
  3. timo86m
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    oh no wait nevermind

    • 10 months ago
  4. SmoothMath
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    Any particular method they want you to use? Do they specify factoring?

    • 10 months ago
  5. burhan101
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    No but isnt that the only way?

    • 10 months ago
  6. SmoothMath
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    Graphing is the easiest.

    • 10 months ago
  7. SmoothMath
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    Graph that bad boy. Look for where it crosses the x axis. Doneso.

    • 10 months ago
  8. burhan101
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    no i have to use an algebraic method

    • 10 months ago
  9. burhan101
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    because like say on an exam, i cant graph that

    • 10 months ago
  10. Mertsj
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    Possible rational roots are :

    • 10 months ago
  11. SmoothMath
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    Okay then your best best is to use the rational root theorem to list possible rational roots. Then check each one to see if it is a valid root.

    • 10 months ago
  12. Mertsj
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    \[\pm1,\pm4,\pm2\]

    • 10 months ago
  13. Mertsj
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    Use synthetic division to see if any of those are actual roots.

    • 10 months ago
  14. SmoothMath
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    Mertsj is correct. The way he got those possible roots is: A: Make a list of factors for the last number (In this case, it's 4) B: Make a list of factors for the first coefficient (In this case, it's 1) Possible rational roots must be of the form \(\huge \frac{\text{things in the first list}}{\text{things in the second list}}\)

    • 10 months ago
  15. Mertsj
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    It is not factorable.

    • 10 months ago
  16. Mertsj
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    So the best approach would be to find where y changes sign. Then you would know there is a root between those two values and you could hone in on it by trial and error. Of if you know calculus, you could use the derivative. What class is this for?

    • 10 months ago
  17. burhan101
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    @Mertsj calculus !

    • 10 months ago
  18. oldrin.bataku
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    they want you to bruteforce using newton's more than likely

    • 10 months ago
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