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anonymous

  • one year ago

Math help!

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  1. anonymous
    • one year ago
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    are you familiar with the topics absolute minima/maxima?

  2. anonymous
    • one year ago
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    Yes

  3. welshfella
    • one year ago
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    |dw:1436463832128:dw|

  4. anonymous
    • one year ago
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    What does that mean?

  5. welshfella
    • one year ago
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    thats the set up find an expression for the area of the rectangle in term of x and y then convert it to one variable so you can find the derivative and equate this to zero.

  6. welshfella
    • one year ago
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    the curve is that of y = 3 - x^2

  7. anonymous
    • one year ago
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    So I derive this?

  8. welshfella
    • one year ago
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    Area of the rectangle A = 2xy and we know that y = 3 - x^2 so plug this expression for y into the expression for the area to get the area in terms of x then find dA/dx and equate to 0 and solve for x to find maxm required

  9. anonymous
    • one year ago
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    * sorry to interfere but quick ques. why is are 2xy? I thought its only xy? thanks!

  10. anonymous
    • one year ago
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    a=6x-2x^3?

  11. welshfella
    • one year ago
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    |dw:1436464453414:dw|

  12. welshfella
    • one year ago
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    yes thats correct for the area

  13. anonymous
    • one year ago
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    a*x*y is only half the area of the whole thing?

  14. welshfella
    • one year ago
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    |dw:1436464614470:dw|

  15. welshfella
    • one year ago
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    xy is the area of half the box

  16. welshfella
    • one year ago
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    agreed?

  17. welshfella
    • one year ago
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    - though i got the x and y wrong way round

  18. welshfella
    • one year ago
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    |dw:1436464860013:dw|

  19. welshfella
    • one year ago
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    A = 6x - 2x^3 dA/dx = 6 - 6x^2 = 0 x^2 = 1 x = 1

  20. welshfella
    • one year ago
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    oh - talking to myself again!!

  21. anonymous
    • one year ago
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    Sorry I lost internet connection yesterday but thank you so much! @welshfella

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