Results 1 to 2 of 2

Math Help - Two function questions....

  1. #1
    M23
    M23 is offline
    Newbie
    Joined
    Jun 2009
    Posts
    19

    Two function questions....

    Given f(x)= sq2x+7 and g(x)=x^2-1 , then the value of g[f(1)] is

    A. 8
    B.(sq7)
    C. 0
    D. 2


    I think this one is B, but am not sure....



    And the second one...

    7. If the equation of a function is y=f(x)=1/2x-5 then the equation of y=f^-1(x) is

    A. y = 2x + 10
    B. y = 2x + 5

    C. y=-1/2x +5

    D. y=1/2x-10








    Thanks for any help!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member I-Think's Avatar
    Joined
    Apr 2009
    Posts
    288
    Good Night.

    Number 1.
    f(x)= \sqrt{2x+7}, g(x)=x^2-1

    Find the value of f(1)
    f(1)=\sqrt{2(1)+7}
    =3
    Find g(3)
    g(3)=3^2-1
    =8

    So you are correct

    Number 2.
    y=f(x)=\frac{1}{2}x-5
    To find y=f^{-1}(x), exchange the y and x in f(x)
    So we now have x=\frac{1}{2}y-5
    Make y the subject of the formula
    x+5=\frac{1}{2}y
    2x+10=y
    f^{-1}(x) =2x+10
    Ans:A
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Polynomial function questions~
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: December 8th 2011, 04:04 PM
  2. Help with some function questions
    Posted in the Discrete Math Forum
    Replies: 3
    Last Post: October 11th 2010, 02:54 AM
  3. Hyperbolic function questions
    Posted in the Algebra Forum
    Replies: 5
    Last Post: April 6th 2010, 04:26 AM
  4. Function questions
    Posted in the Pre-Calculus Forum
    Replies: 4
    Last Post: April 29th 2008, 12:09 AM
  5. 3 Function/Pre-Calculus Questions
    Posted in the Pre-Calculus Forum
    Replies: 7
    Last Post: October 28th 2006, 02:37 PM

Search Tags


/mathhelpforum @mathhelpforum