Results 1 to 11 of 11

Math Help - domain and range URGENT!!!!!!!

  1. #1
    Member
    Joined
    Jul 2007
    Posts
    75

    Thumbs down domain and range URGENT!!!!!!!

    Find the domain and range of the function: f(x)=(4/5) l8-xl
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,845
    Thanks
    320
    Awards
    1
    Quote Originally Posted by iheartthemusic29 View Post
    Find the domain and range of the function: f(x)=(4/5) l8-xl
    Domains are easy. What values of x does f(x) not exist? There are no restrictions here so the domain of the function is all real numbers.

    Ranges are harder. When all else fails, graph it. In this case we can see that the minimum of the function is at x = 8. There is no upper bound. So the range is  [0, \infty ) .

    -Dan
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Jul 2007
    Posts
    75

    Question Ummmmm

    I'm still confused. What does the 8 have to do with it? Where did the zero come from? Why is it infinity?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Math Engineering Student
    Krizalid's Avatar
    Joined
    Mar 2007
    From
    Santiago, Chile
    Posts
    3,654
    Thanks
    13
    Why post again this?

    Look at here

    Dan gave you a full explanation.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Member
    Joined
    Jul 2007
    Posts
    75

    Exclamation

    because I didn't understand it!
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Math Engineering Student
    Krizalid's Avatar
    Joined
    Mar 2007
    From
    Santiago, Chile
    Posts
    3,654
    Thanks
    13
    Then you should've posted there, not to create another thread.

    Follow Math Help Forum on Facebook and Google+

  7. #7
    Member
    Joined
    Jul 2007
    Posts
    75

    Question

    well I knew I had posted it it once before but I couldn't find it again! sorry! and I'm still not understanding it!
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,845
    Thanks
    320
    Awards
    1
    Quote Originally Posted by iheartthemusic29 View Post
    I'm still confused. What does the 8 have to do with it? Where did the zero come from? Why is it infinity?
    Did you graph the function? (See below.)

    -Dan
    Attached Thumbnails Attached Thumbnails domain and range URGENT!!!!!!!-graph.jpg  
    Follow Math Help Forum on Facebook and Google+

  9. #9
    Member
    Joined
    Jul 2007
    Posts
    75

    Question

    can someone explain this in words to me? so is it all positive real numbers?
    Follow Math Help Forum on Facebook and Google+

  10. #10
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,845
    Thanks
    320
    Awards
    1
    Quote Originally Posted by iheartthemusic29 View Post
    can someone explain this in words to me? so is it all positive real numbers?
    Almost. The range is all positive real numbers and 0.

    Is it the notation  [0, \infty) that's bothering you?

    -Dan
    Follow Math Help Forum on Facebook and Google+

  11. #11
    Member
    Joined
    Jul 2007
    Posts
    75
    yes, but I think I understand it now.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. domain and range
    Posted in the Algebra Forum
    Replies: 1
    Last Post: April 12th 2010, 12:37 PM
  2. Replies: 6
    Last Post: September 16th 2009, 06:25 AM
  3. Domain & Range
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: September 7th 2009, 11:05 AM
  4. Domain and range
    Posted in the Pre-Calculus Forum
    Replies: 7
    Last Post: January 24th 2009, 03:53 AM
  5. range and domain
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: November 16th 2008, 01:53 PM

Search Tags


/mathhelpforum @mathhelpforum