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kymber

How to find the maximum or minimum value of a quadratic function?

  • one year ago
  • one year ago

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  1. 2le
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    You look at the vertex. Are you at the calculus level or the algebra level?

    • one year ago
  2. ganeshie8
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    see the sign of x^2 coeffecient

    • one year ago
  3. kymber
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    Algrebra II, year three in high school. It's the same as the vertex?

    • one year ago
  4. ganeshie8
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    correct, vertex gives us max/min value. if x^2 coefficient is -ve, its min if x^2 coefficient is +ve, its max

    • one year ago
  5. ganeshie8
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    its the opposite actually. if x^2 coefficient is -ve, its max if x^2 coefficient is +ve, its min

    • one year ago
  6. 2le
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    What @ganeshie8 said, that will tell you whether the parabola faces up or down. The point at the vertex will be a min or a max depending on that coefficient.

    • one year ago
  7. ganeshie8
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    |dw:1349465625929:dw|

    • one year ago
  8. ganeshie8
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    so we have minimum value there

    • one year ago
  9. kymber
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    So how do you find the value of it?

    • one year ago
  10. ganeshie8
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    max/min value = f(-b/2a)

    • one year ago
  11. ganeshie8
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    actually it comes from the formula for vertex, vertex = (-b/2a, f(-b/2a))

    • one year ago
  12. phi
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    for parabola f(x)= a x^2 + b x +c the x coordinate of the vertex is -b/(2a)

    • one year ago
  13. kymber
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    Um, like this? |dw:1349465829395:dw|

    • one year ago
  14. CliffSedge
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    Given \[ax^2+bx+c=a(x-h)^2+k\] The vertex is located at (h, k).

    • one year ago
  15. ganeshie8
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    |dw:1349465949629:dw|

    • one year ago
  16. ganeshie8
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    that gives the x-coordinate only, y-coordinate gives the max/min value.

    • one year ago
  17. ganeshie8
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    coordinate is just a number i think

    • one year ago
  18. kymber
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    So how do I find the y-coordinate?

    • one year ago
  19. ganeshie8
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    since you got, x-coordinate of vertex = -b/2a = 5

    • one year ago
  20. ganeshie8
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    put that x value = 5, in the quadratic, it gives u y-coordinate of vertex

    • one year ago
  21. phi
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    notice in x^2 -10x +25 b is -10 (negative 10) -b/2a is +10/2*1= 10/2 = +5 use 5 for x in the equation to find the y value

    • one year ago
  22. kymber
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    I got it! Thanks guys \(\Large\ddot\smile\)

    • one year ago
  23. ganeshie8
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    glad to hear friend :)

    • one year ago
  24. phi
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    hopefully you got y=0 so the vertex is at (5,0) and the min value is 0

    • one year ago
  25. ganeshie8
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    and hw do i get that

    • one year ago
  26. ganeshie8
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    smiley..

    • one year ago
  27. kymber
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    Yep, I got 0. the smiley is \large\ddot\smile :P

    • one year ago
  28. ganeshie8
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    \( \large\ddot\smile \) ah latex is beautifyul :)

    • one year ago
  29. kymber
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    Yes it is :D

    • one year ago
  30. CliffSedge
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    Thanks, @kymber for teaching us something. \[\large \ddot \smile\] Awesome.

    • one year ago
  31. kymber
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    Hehe \(\huge\ddot\smile\)

    • one year ago
  32. hartnn
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    yeah , kymber also taught me to draw heart ♥ \(\huge \color{red}{♥}\)

    • one year ago
  33. CliffSedge
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    Nice!

    • one year ago
  34. kymber
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    \(\Huge\color{pink}{❥}\) Sideways!

    • one year ago
  35. ganeshie8
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    i thought only AccessDenied is the latex guru... we have so many experts over here hmm :)

    • one year ago
  36. ganeshie8
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    but thats cheating... thats not latex, u using unicode i guess

    • one year ago
  37. CliffSedge
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    You're blowing my mind, @kymber !

    • one year ago
  38. kymber
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    Lol yeah.. it's not a \(\LaTeX\) command. Just alt codes :|

    • one year ago
  39. hartnn
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    still its cool :)

    • one year ago
  40. kymber
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    :D

    • one year ago
  41. ganeshie8
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    :) yea these things i can see also. but sometime back i tried to use crossed swords unicode, and it didnt show up in many browsers :( from then i stopped using unicode, not sure why only few unicode characters show up...

    • one year ago
  42. ganeshie8
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    this one : http://www.fileformat.info/info/unicode/char/2694/index.htm see if u can get this here...

    • one year ago
  43. kymber
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    \(\Huge{⚔}\)

    • one year ago
  44. kymber
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    Lol.

    • one year ago
  45. ganeshie8
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    i see a box, what u see at ur end hmm

    • one year ago
  46. kymber
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    :| I see the swords..

    • one year ago
  47. hartnn
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    i see box also

    • one year ago
  48. kymber
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    What browser are you guys using?

    • one year ago
  49. hartnn
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    chrome O.o

    • one year ago
  50. ganeshie8
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    chrome too

    • one year ago
  51. kymber
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    I'm using Mozilla :P

    • one year ago
  52. ganeshie8
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    firefox ?

    • one year ago
  53. hartnn
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    letme login through mozilla

    • one year ago
  54. kymber
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    Yeah. I switched to Chrome and it's a box. Use Mozilla! :P

    • one year ago
  55. ganeshie8
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    mozilla wins !

    • one year ago
  56. hartnn
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    what kind of black magic is this!

    • one year ago
  57. CliffSedge
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    Firefox is simply superior . .

    • one year ago
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