Results 1 to 6 of 6

Math Help - Graphing a Parabola in Standard Form

  1. #1
    Junior Member
    Joined
    Sep 2009
    Posts
    49

    Graphing a Parabola in Standard Form

    Sketch the graph of f(x)= 2x^2 8x + 7 and identify the vertex and the axis of the parabola.

    i have no idea how to do it.

    can you please give me step by step on how to do it.

    like what is the first step and so on.

    thank you.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,831
    Thanks
    1602

    Re: Graphing a Parabola in Standard Form

    Quote Originally Posted by Candy101 View Post
    Sketch the graph of f(x)= 2x^2 8x + 7 and identify the vertex and the axis of the parabola.

    i have no idea how to do it.

    can you please give me step by step on how to do it.

    like what is the first step and so on.

    thank you.
    Start by taking out 2 as a factor, then complete the square on the remaining stuff.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Sep 2009
    Posts
    49

    Re: Graphing a Parabola in Standard Form

    ok i got this far and now im stuck, and i don't know is this step is correct

    f(x)= 2(x^2 +4x+4)7-4

    i do not what to do after this.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,831
    Thanks
    1602

    Re: Graphing a Parabola in Standard Form

    Quote Originally Posted by Candy101 View Post
    ok i got this far and now im stuck, and i don't know is this step is correct

    f(x)= 2(x^2 +4x+4)7-4

    i do not what to do after this.
    No, when you take out 2 as a factor, you divide every term by 2.

    It should be \displaystyle  2x^2 + 8x + 7 = 2\left(x^2 + 4x + \frac{7}{2}\right)

    Now try to complete the square on the stuff in the brackets.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member
    Joined
    Sep 2009
    Posts
    49

    Re: Graphing a Parabola in Standard Form

    so will it be

    \displaystyle  2\left(x^2 + 4x + \frac{7}{4}+4\right) ???

    if so then what do i do after that


    i watch some videos on it, and this is what i came up with

    \displaystyle  2\left(x^2 + 4x +4 \)2(-4\right)+7

    \displaystyle  2\left(x^2 + 4x +4 \)-8\right+7 = \displaystyle  2\left(x^2 + 4x +4 \)-1\right

    then i write it in standard form \displaystyle  f(x)= a\left(x- h\)^2+k\right

    isnt that correct?
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor
    Prove It's Avatar
    Joined
    Aug 2008
    Posts
    11,831
    Thanks
    1602

    Re: Graphing a Parabola in Standard Form

    Quote Originally Posted by Candy101 View Post
    so will it be

    \displaystyle  2\left(x^2 + 4x + \frac{7}{4}+4\right) ???

    if so then what do i do after that


    i watch some videos on it, and this is what i came up with

    \displaystyle  2\left(x^2 + 4x +4 \)2(-4\right)+7

    \displaystyle  2\left(x^2 + 4x +4 \)-8\right+7 = \displaystyle  2\left(x^2 + 4x +4 \)-1\right

    then i write it in standard form \displaystyle  f(x)= a\left(x- h\)^2+k\right

    isnt that correct?
    No, you can't just add a term to something and expect it to be equal to what you originally started with. Whatever extra term you add, you have to subtract straight away.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Confusion! Graphing a Parabola in Standard Form
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: September 15th 2009, 01:42 PM
  2. Parabola in Standard Form
    Posted in the Algebra Forum
    Replies: 4
    Last Post: December 29th 2008, 10:18 PM
  3. Standard Form of Parabola
    Posted in the Pre-Calculus Forum
    Replies: 7
    Last Post: August 14th 2008, 04:51 PM
  4. Standard form of parabola
    Posted in the Pre-Calculus Forum
    Replies: 5
    Last Post: June 25th 2008, 10:56 PM
  5. parabola standard form help
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: September 5th 2007, 08:47 AM

Search Tags


/mathhelpforum @mathhelpforum