Is this calc problem, solution wrong?

Discussion in 'Undergraduate Math' started by Patrick, May 20, 2005.

  1. Patrick

    Patrick Guest

    I'm to determine the volume of the solid defined by the areas:

    y = x^2 , y = 4; rotated about the line y = 4.

    I expect to integrate with respect to x from 0 to 2.

    I think the correct area function is:

    A(x) = pi(4-x^2)^2 = pi (16 - 8x^2 + x^4)

    So I integrate:

    pi * INT[ 16 - 8x^2 + x^4 ] dx from 0 to 2.

    Does it appear that I'm ok up to this point or
    have I made a mistake.

    Thanks.
     
    Patrick, May 20, 2005
    #1
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  2. -2 to 2
    You did the area within x = 0, y = 4, y = x^2
     
    William Elliot, May 20, 2005
    #2
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  3. Patrick

    Mkajuma Guest

    Draw the picture and you will see the correct limits. Think negative!
     
    Mkajuma, May 20, 2005
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