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kymber

  • 2 years ago

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

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

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

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

  4. ganeshie8
    • 2 years ago
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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

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

  6. 2le
    • 2 years ago
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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.

  7. ganeshie8
    • 2 years ago
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    |dw:1349465625929:dw|

  8. ganeshie8
    • 2 years ago
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    so we have minimum value there

  9. kymber
    • 2 years ago
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    So how do you find the value of it?

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

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

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

  13. kymber
    • 2 years ago
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    Um, like this? |dw:1349465829395:dw|

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

  15. ganeshie8
    • 2 years ago
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    |dw:1349465949629:dw|

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

  17. ganeshie8
    • 2 years ago
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    coordinate is just a number i think

  18. kymber
    • 2 years ago
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    So how do I find the y-coordinate?

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

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

  21. phi
    • 2 years ago
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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

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

  23. ganeshie8
    • 2 years ago
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    glad to hear friend :)

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

  25. ganeshie8
    • 2 years ago
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    and hw do i get that

  26. ganeshie8
    • 2 years ago
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    smiley..

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

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

  29. kymber
    • 2 years ago
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    Yes it is :D

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

  31. kymber
    • 2 years ago
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    Hehe \(\huge\ddot\smile\)

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

  33. CliffSedge
    • 2 years ago
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    Nice!

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

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

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

  37. CliffSedge
    • 2 years ago
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    You're blowing my mind, @kymber !

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

  39. hartnn
    • 2 years ago
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    still its cool :)

  40. kymber
    • 2 years ago
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    :D

  41. ganeshie8
    • 2 years ago
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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...

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

  43. kymber
    • 2 years ago
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    \(\Huge{⚔}\)

  44. kymber
    • 2 years ago
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    Lol.

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

  46. kymber
    • 2 years ago
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    :| I see the swords..

  47. hartnn
    • 2 years ago
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    i see box also

  48. kymber
    • 2 years ago
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    What browser are you guys using?

  49. hartnn
    • 2 years ago
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    chrome O.o

  50. ganeshie8
    • 2 years ago
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    chrome too

  51. kymber
    • 2 years ago
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    I'm using Mozilla :P

  52. ganeshie8
    • 2 years ago
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    firefox ?

  53. hartnn
    • 2 years ago
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    letme login through mozilla

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

  55. ganeshie8
    • 2 years ago
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    mozilla wins !

  56. hartnn
    • 2 years ago
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    what kind of black magic is this!

  57. CliffSedge
    • 2 years ago
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    Firefox is simply superior . .

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