Algebra

posted by .

Hello. I am trying to solve quadratic functions but I'm having difficulty understanding. Here is my work so far...

y=3x^2 + 12x + 9
12/6 = -2 = y
3(-2)^2 + 12(-2) + 9 = -3
x=0 y=9 (0,9)

Would I just plug in 1 and 2 for x and then reflect it while i'm graphing?

So, if I do that, should it come out...

x=1
-----
y=3(1)^2 + 12(1) + 9
y=3+12+9
y=24 (1,24)

x=2
------
y=3(2)^2 + 12(2) + 9
y=12+24+9
y=45 (2,45)

Would this be correct?

  • Algebra -

    you are correct on the points 1,24 and 2,45

    The first part, I do not understand what you were doing.

  • Algebra -

    y=3x^2 + 12x + 9

    you are correct that when x = 0, y = 9 so (0,9) is on it

    However I do not know what else you are doing.
    I generally complete the square to find the axis of symmetry
    3x^2 + 12x + 9 = y
    get one by x^2 so divide by 3
    x^2 + 4 x + 3 = y/3
    subtract 3 from both sides
    x^2+4x = y/3 - 9/3 =
    add (half of 4)^2 to both sides
    x^2 + 4 x + 4 = y/3 -9/3 + 12/3
    (x+2)^2 = (1/3)(y+3)
    vertex at (-2, -3)
    vertical axis of symmetry at x = -2

  • Algebra -

    Well, I'm trying to find two different points by changing the x value since I need to graph these points and then reflect it. I hope this helps you a little.

  • Algebra -

    ok, well reflect it about the line x = -2
    and the bottom is at (-2,-3)
    Your (1,24) and your (2,45) are fine
    so
    first point is the bottom (-2,-3)
    next is your (1,24)
    the reflection of that about x = -2 is
    3 to the left of -2 which is (-5,24)

    next do your (2,45)
    that is four to the right of the line of symmetry so go four to the left of -2 to -6
    so (-6,45)

  • Algebra -

    this might help:
    http://www.purplemath.com/modules/sqrvertx.htm

  • Algebra -

    and this:
    http://uncw.edu/courses/mat111hb/pandr/quadratic/quadratic.html

Respond to this Question

First Name
School Subject
Your Answer

Similar Questions

  1. algebra II

    Solve the quadratic equation 12x^2 + 36a^2= 43ax by factorization Show your work
  2. math

    i'm having difficulty understanding radicals.. I don't know how to type the radical sign on here so i'll use parenthesis instead like for instance 17+34 (192)/34 how would u solve that.. also how do u decipher the two multiples of …
  3. Algebra 1

    Hello. I am having a bit of trouble understanding the following "Solve by Graphing. 3x + y = 5 -2x + 3y = 4" I know you can't see the graphing on this site, but I would really appreciate it if someone points me in the right direction …
  4. Algebra

    how do you solve this quadratic equation?
  5. Pre-Cal

    I'm trying to put this parabola in standard form which is: (y-k)^2=4p(x-h) The equation is x=(1/12)(y-2)^2 +6 Here is what i have so far: x=(1/12)(y-2)^2 +6 -6 -6 x-6=(1/12)(y-2)^2 *12 *12 Would it be 12x-6 OR 12x-72?
  6. algebra

    Which of the quadratic functions has the narrowest graph?
  7. ALgebra

    JUST A MOM TRYING TO HELP MY CHILD WITH UNDERSTANDING. DON'T KNOW HOW TO SOLVE THE SECOND PROBLEM Write equation for each segment. show your work. (-4,-3) (-3,-3) Y = mx + b 3 = 0(-4) +b 3 = 0 + b Y = x - 3 (1,-5) (6,-2) Y = mx + b …
  8. Algebra 2

    Solve Quadratic System x^2+y^2=2 x^2-6y=10 Please SHOW WORK I'm having trouble
  9. Algebra 2

    I really need help understanding ho to solve combination functions here is a specific problem I am struggling with. Let f(x) = x - 2 and g(x) = x^2 - 7x - 9. Find f(g(-1)).
  10. Algebra

    Which quadratic equation has roots -1+4i and -1-4i ?

More Similar Questions