Results 1 to 2 of 2

Math Help - Domain and Range

  1. #1
    Junior Member
    Joined
    Jun 2010
    Posts
    35

    Domain and Range

    Determine whether or not the equation defines y as a function of x. if it is a function, find the domain and range. x+y=9, x+y^3=8, x^2+y=16
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member eumyang's Avatar
    Joined
    Jan 2010
    Posts
    278
    Thanks
    1
    Quote Originally Posted by soni View Post
    Determine whether or not the equation defines y as a function of x. if it is a function, find the domain and range. x+y=9, x+y^3=8, x^2+y=16
    Solve each equation for y. For the first one,
    x + y = 9
    y = -x + 9
    The graph of this is a line with slope -1 and y-intercept of 9 -- it's clearly a function. There are no restrictions for x (for example, x is not in the denominator or underneath the square root) so the domain is all real numbers. You can also see that the range is all real numbers.

    What would be an instance of an equation not being a function? If you take an equation like this and solve for y:
    y^2=x
    y=\sqrt{x} OR
    y=-\sqrt{x}
    You actually get two equations. The graph of y^2=x is a parabola opening to the right; it's not a function (apply the vertical line test).
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 6
    Last Post: September 16th 2009, 06:25 AM
  2. Domain and Range of f(x,y)
    Posted in the Calculus Forum
    Replies: 4
    Last Post: October 1st 2008, 09:20 PM
  3. domain and range
    Posted in the Pre-Calculus Forum
    Replies: 4
    Last Post: September 30th 2008, 02:54 AM
  4. Range and Domain
    Posted in the Pre-Calculus Forum
    Replies: 5
    Last Post: September 28th 2008, 04:42 PM
  5. domain and range
    Posted in the Pre-Calculus Forum
    Replies: 5
    Last Post: July 17th 2007, 01:34 PM

Search Tags


/mathhelpforum @mathhelpforum