Results 1 to 5 of 5

Math Help - greatest value

  1. #1
    Member
    Joined
    Aug 2009
    Posts
    211

    greatest value

    i've been asked to find the greatest value of \frac {1}{x} from 3(x + 2)^2 + 5 the answer is 1/5 but i was wondering if someone could show me how they would come to that answer, thanks

    ps there is supposed to be a function symbol (f) in front of the x but i don't know how to write it out
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor red_dog's Avatar
    Joined
    Jun 2007
    From
    Medgidia, Romania
    Posts
    1,245
    Thanks
    1
    Do you mean to find the maximum of \frac{1}{f(x)} if f(x)=3(x+2)^2+5 ?
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Aug 2009
    Posts
    211
    yeah thats the one
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Joined
    Sep 2008
    From
    West Malaysia
    Posts
    1,261
    Quote Originally Posted by mark View Post
    i've been asked to find the greatest value of \frac {1}{x} from 3(x + 2)^2 + 5 the answer is 1/5 but i was wondering if someone could show me how they would come to that answer, thanks

    ps there is supposed to be a function symbol (f) in front of the x but i don't know how to write it out
    1/f(x) is maximum when f(x) is minimum . The minimum of f(x) is 5 so the answer is correct .
    Follow Math Help Forum on Facebook and Google+

  5. #5
    MHF Contributor red_dog's Avatar
    Joined
    Jun 2007
    From
    Medgidia, Romania
    Posts
    1,245
    Thanks
    1
    In this case the maximum of \frac{1}{f(x)} is reached when f(x) is minimum. The minimum of f(x) is 5, when x=-2.

    Then the maximum of \frac{1}{f(x)} is \frac{1}{5}.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. The greatest value
    Posted in the Algebra Forum
    Replies: 1
    Last Post: February 22nd 2010, 06:39 PM
  2. Replies: 3
    Last Post: November 12th 2009, 01:27 PM
  3. Greatest integer of sum
    Posted in the Algebra Forum
    Replies: 7
    Last Post: May 10th 2009, 08:30 PM
  4. integers from greatest to least
    Posted in the Algebra Forum
    Replies: 8
    Last Post: April 28th 2008, 08:41 PM
  5. Greatest product from a sum
    Posted in the Number Theory Forum
    Replies: 8
    Last Post: July 28th 2007, 06:14 AM

Search Tags


/mathhelpforum @mathhelpforum