Results 1 to 4 of 4

Math Help - Calculus Problem

  1. #1
    Member
    Joined
    Jan 2006
    Posts
    118

    Calculus Problem

    Please See Attached
    Attached Thumbnails Attached Thumbnails Calculus Problem-calculus.jpg  
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Global Moderator

    Joined
    Nov 2005
    From
    New York City
    Posts
    10,616
    Thanks
    9
    You are going to be using the formula
    V=\int^b_aA(x)dx
    First see that you are taking the integral from x=0 until x=8 that is when it intersects the x and y axes.

    Now you need to find A(x):
    Notice that x+2y=8 implies y=-\frac{1}{2}x+8.
    At x the width of the line perpendicular to the x-axis is then -\frac{1}{2}x+8. But this is the diameter of the circle. Thus, its radius is -\frac{1}{4}x+4.
    The area of this cross section (semicircle) is
    \pi \frac{1}{2}\left(-\frac{1}{4}x+4\right)^2 (remember the 1/2 it is semi-circle )
    Thus,
    V=\pi \int^8_0\frac{1}{2}\left(-\frac{1}{4}x+4\right)^2dx=\pi \cdot 37.\bar 3\approx 116
    I think there is something wrong with your choices.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Nov 2005
    From
    Wethersfield, CT
    Posts
    92
    Dear PHckr:

    Line #5 of your narrative reads:


    Notice that implies .

    Do you see the problem?

    Regards,

    Rich B.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Global Moderator

    Joined
    Nov 2005
    From
    New York City
    Posts
    10,616
    Thanks
    9
    Quote Originally Posted by Rich B.
    Dear PHckr:

    Line #5 of your narrative reads:


    Notice that implies .

    Do you see the problem?

    Regards,

    Rich B.
    Sorry
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Help with calculus problem
    Posted in the Calculus Forum
    Replies: 1
    Last Post: February 25th 2010, 11:05 AM
  2. Replies: 1
    Last Post: June 7th 2008, 11:47 AM
  3. pre calculus problem
    Posted in the Trigonometry Forum
    Replies: 4
    Last Post: May 16th 2007, 11:30 AM
  4. Help with this Calculus Problem
    Posted in the Calculus Forum
    Replies: 1
    Last Post: May 30th 2006, 06:03 PM
  5. Calculus Problem!!!!
    Posted in the Calculus Forum
    Replies: 1
    Last Post: March 18th 2006, 10:10 PM

Search Tags


/mathhelpforum @mathhelpforum