Results 1 to 4 of 4

Math Help - Polynomial

  1. #1
    Newbie
    Joined
    Apr 2007
    Posts
    16

    Exclamation Polynomial

    Hey, there are a few more questions i am strugling with.

    2(i) Express 3x+12x+7 in the form 3(x+a) +b

    I think its 3(x+2)-5 is that right?

    (ii) Hence write down the equation of the line of symmetry of the curve y=3x+12x+7

    Would appreciate the help!

    Next one:

    10(iv) Given that 24x+3y+2=0 is the equation of the tangent to the curve at the point (p,q), find p and q. (The curve is y=1/3x-9x.)

    Thanks for all the help you guys are giving me!
    Last edited by LoveDeathCab; April 24th 2007 at 12:34 PM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by LoveDeathCab View Post
    Hey, there are a few more questions i am strugling with.

    2(i) Express 3x+12x+7 in the form 3(x+a) +b

    I think its 3(x+2)-5 is that right?

    We need to complete the square here, i hope that's what you did. perhaps you're not comfortable with it? if you have any questions, just ask away. anyway, here goes

    3x^2 + 12x + 7 = 3(x^2 + 4x) + 7
    ......................= 3(x^2 + 4x + (2)^2 - (2)^2) + 7

    ......................= 3[(x + 2)^2 - 4] + 7
    ......................= 3(x + 2)^2 - 12 + 7
    ......................= 3(x + 2)^2 - 5

    (ii) Hence write down the equation of the line of symmetry of the curve y=3x+12x+7

    Now a parabola is symmetric about it's vertex. and when a parabola is written in the form:
    y = a(x - h)^2 + k
    then the vertex is given by (h,k)

    we have
    3(x + 2)^2 - 5 so our vertex is at (-2,-5)
    since this is a parabola with a vertical axis (opens up or down, in this case up) the line of symmetry is just x = -2
    Last edited by Jhevon; April 24th 2007 at 02:32 PM. Reason: I added wrong....lol. Thanks for looking out LoveDeathCab
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Apr 2007
    Posts
    16
    Quote Originally Posted by Jhevon View Post
    ......................= 3(x + 2)^2 - 12 + 7
    ......................= 3(x + 2)^2 - 4
    Hey, is there a small mistake here? Should it be -5? -12+7=-5? Just wondering cause i got 3(x + 2)^2 - 5

    Thanks
    Follow Math Help Forum on Facebook and Google+

  4. #4
    is up to his old tricks again! Jhevon's Avatar
    Joined
    Feb 2007
    From
    New York, USA
    Posts
    11,663
    Thanks
    3
    Quote Originally Posted by LoveDeathCab View Post
    Hey, is there a small mistake here? Should it be -5? -12+7=-5? Just wondering cause i got 3(x + 2)^2 - 5

    Thanks
    Yes, you are correct, it should be -5
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 1
    Last Post: October 23rd 2011, 07:36 AM
  2. Replies: 1
    Last Post: February 24th 2011, 07:46 PM
  3. Replies: 1
    Last Post: December 15th 2009, 08:26 AM
  4. [SOLVED] dividing polynomial by a polynomial
    Posted in the Algebra Forum
    Replies: 1
    Last Post: February 3rd 2008, 03:00 PM
  5. dividing a polynomial by a polynomial
    Posted in the Algebra Forum
    Replies: 1
    Last Post: August 2nd 2005, 01:26 AM

Search Tags


/mathhelpforum @mathhelpforum