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mathcalculus Group Title

Help (Attached below) Determine the extrema of below on the given interval

  • one year ago
  • one year ago

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  1. mathcalculus Group Title
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    • one year ago
  2. mathcalculus Group Title
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    i know we have to find the derivative and set it to zero

    • one year ago
  3. mathcalculus Group Title
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    i got x= 8 and x= 2/9

    • one year ago
  4. mathcalculus Group Title
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    now to have the intervals, im a little lost on...

    • one year ago
  5. mathcalculus Group Title
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    would there only be 2 intervals?

    • one year ago
  6. mathcalculus Group Title
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    or 3? 0-2/9 then 2/9-8 and 8-infinity?

    • one year ago
  7. campbell_st Group Title
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    ok... so whats the derivative...?

    • one year ago
  8. mathcalculus Group Title
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    9x^2-74x+16

    • one year ago
  9. mathcalculus Group Title
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    then i set it to = 0

    • one year ago
  10. campbell_st Group Title
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    ok... so what are the solutions...?

    • one year ago
  11. mathcalculus Group Title
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    x=8 and x=2/9

    • one year ago
  12. mathcalculus Group Title
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    critical numbers

    • one year ago
  13. campbell_st Group Title
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    yep... so on [0, 4] substitute x = 0, 2/9 and 4 into the original equation and find the corresponding values...

    • one year ago
  14. mathcalculus Group Title
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    why 4?

    • one year ago
  15. mathcalculus Group Title
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    thanks

    • one year ago
  16. mathcalculus Group Title
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    isn't 4 a y?

    • one year ago
  17. mathcalculus Group Title
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    and what 8?

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  18. mathcalculus Group Title
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    because the 2 critical numbers are 8 and 2/9

    • one year ago
  19. campbell_st Group Title
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    well (a) is asking for the location of that min and max on the interval x = 0 to x = 4 and as x = 2/9 is a critical point...you don't know its nature

    • one year ago
  20. mathcalculus Group Title
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    ooooooh, 8 would be the other one

    • one year ago
  21. mathcalculus Group Title
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    let me try it

    • one year ago
  22. campbell_st Group Title
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    so the value x =0 is f(0) = 2 x = 2/9 f(2/9) = 3.76 x = 4 f(4) = ?

    • one year ago
  23. mathcalculus Group Title
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    -334

    • one year ago
  24. mathcalculus Group Title
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    so the max is 3.76 and min is -334?

    • one year ago
  25. campbell_st Group Title
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    thats correct...

    • one year ago
  26. campbell_st Group Title
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    so just test x = -9, x = 8 and x = 9... and see what happens... I think x = 2/9 remains the max

    • one year ago
  27. campbell_st Group Title
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    its an add interval since x = -9 gives a very large negative number

    • one year ago
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