Results 1 to 5 of 5

Math Help - Domain And Range

  1. #1
    Junior Member
    Joined
    May 2009
    Posts
    68

    Domain And Range

    1) State the domain and range of each of the following functions:
    a) y = 3x + 4
    b) y = 3(x-4)^2 +5
    c) y = √ 2x-10
    (the root is over all the numbers for c)
    d) y = √ -x^2 + 4
    (the square root sign is over all the numbers for d) as well
    e) y = 2 |1x |17
    f) y = x/ (x^2-x-6)


    Can someone help me find these plus explain why for d) e) and f)
    Follow Math Help Forum on Facebook and Google+

  2. #2
    No one in Particular VonNemo19's Avatar
    Joined
    Apr 2009
    From
    Detroit, MI
    Posts
    1,823
    Quote Originally Posted by foreverbrokenpromises View Post
    1) State the domain and range of each of the following functions:
    a) y = 3x + 4
    b) y = 3(x-4)^2 +5
    c) y = √ 2x-10
    (the root is over all the numbers for c)
    d) y = √ -x^2 + 4
    (the square root sign is over all the numbers for d) as well
    e) y = 2 |1x |17
    f) y = x/ (x^2-x-6)


    Can someone help me find these plus explain why for d) e) and f)
    You can think of the domain as all the numbers that x is 'allowed' to be.

    As in c)... You know that you can't take the square root of a negative number and get a real number. So, x can only be those numbers that make the radicand greater than or equal to zero. In other words, solve

    2x-10\geq0

    and you will have your domain.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Member
    Joined
    Nov 2008
    From
    Ontario
    Posts
    80
    (f) You cannot include in the domain where the function is undefined, therefore areas where the dominator of a rational function is equal to zero should not be included in the domain.

    So the domain is (-∞, -2) U (-2, 3) U (3, ∞)
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member
    Joined
    May 2009
    Posts
    68
    Thanks
    I've figured out a) b) and c)

    but i still cant figure out how to complete the following:

    d) y = √-x^2 +4
    e) y = 2 |1-x|-17
    f) y= x/ (x^2-x-6)

    pls help!
    Follow Math Help Forum on Facebook and Google+

  5. #5
    -1
    e^(i*pi)'s Avatar
    Joined
    Feb 2009
    From
    West Midlands, England
    Posts
    3,053
    Thanks
    1
    Quote Originally Posted by foreverbrokenpromises View Post
    Thanks
    I've figured out a) b) and c)

    but i still cant figure out how to complete the following:

    d) y = √-x^2 +4
    e) y = 2 |1-x|-17
    f) y= x/ (x^2-x-6)

    pls help!
    For d apply the principle VonNemo19 outlined in post 2.

    d) -x^2+4 \geq 0 \: \: \rightarrow \: \: 4-x^2 \geq 0

    (2-x)(2+x) \geq 0.

    Spoiler:
    -2 \leq x \leq 2


    e) What values of x are not allowed in this linear equation?

    Spoiler:
    There are none so x is all the real numbers


    f) x^2-x-6=(x+2)(x-3). Remember that any value that makes the denominator equal to 0 is not allowed

    Spoiler:
    x \in \mathbb{R} \: , \: x \neq -2,3
    Last edited by e^(i*pi); December 12th 2009 at 12:33 PM. Reason: typo
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Domain and range
    Posted in the Algebra Forum
    Replies: 2
    Last Post: April 14th 2010, 02:09 AM
  2. Domain and Range
    Posted in the Pre-Calculus Forum
    Replies: 9
    Last Post: January 13th 2010, 07:12 AM
  3. Replies: 6
    Last Post: September 16th 2009, 06:25 AM
  4. Domain And Range
    Posted in the Pre-Calculus Forum
    Replies: 4
    Last Post: May 3rd 2008, 09:31 PM
  5. Domain and range?
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: April 22nd 2008, 04:45 AM

Search Tags


/mathhelpforum @mathhelpforum