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Spartan_Of_Ares

  • 2 years ago

Determine whether the graph of y = x^2 + 2x − 8 has a maximum or minimum point, then find the maximum or minimum value

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  1. Spartan_Of_Ares
    • 2 years ago
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    @zaynahf can you please help me?

  2. zaynahf
    • 2 years ago
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    Just a minute, im getting my notes

  3. zaynahf
    • 2 years ago
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    Ok do you know which way the parabola is going? Up or down?

  4. Spartan_Of_Ares
    • 2 years ago
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    i think up because the x^2 is positive

  5. Spartan_Of_Ares
    • 2 years ago
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    yeah it opens up

  6. zaynahf
    • 2 years ago
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    Right! So based on that, it tells you whether your vertex will have a maximum or minimum value. When it is opening up (a value is +), there will be a minimum because the vertex is on the bottom, the lowest point of the parabola. When it is opening down (a value is -), there will be a maximum value because the vertex is at the top, the highest point of the parabola. When naming the min/max, you only use the y value of the vertex. Example:|dw:1357599979562:dw|

  7. zaynahf
    • 2 years ago
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    One more thing: IF you know how to find a vertex when it is in standard form, you can do that, but personally i find it easier to first complete the square (make it into vertex form). If you need to know how to do either, let me know.

  8. Spartan_Of_Ares
    • 2 years ago
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    how do i put it in vertex form?

  9. zaynahf
    • 2 years ago
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    I'll give you an example one, if you dont mind

  10. Spartan_Of_Ares
    • 2 years ago
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    thats fine

  11. zaynahf
    • 2 years ago
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    |dw:1357600335929:dw||dw:1357600792411:dw|

  12. Spartan_Of_Ares
    • 2 years ago
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    oh that make sense they dont teach that in virtual school

  13. zaynahf
    • 2 years ago
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    I have a link if you want it

  14. Spartan_Of_Ares
    • 2 years ago
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    OK

  15. zaynahf
    • 2 years ago
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    http://www.youtube.com/watch?v=aDHq_FoRxZQ Explains it better than i did

  16. Spartan_Of_Ares
    • 2 years ago
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    would the vertex be (-0.33,-10.33)?

  17. zaynahf
    • 2 years ago
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    No o.o

  18. zaynahf
    • 2 years ago
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    How did you get that?

  19. Spartan_Of_Ares
    • 2 years ago
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    -1,-9 if i round?

  20. Spartan_Of_Ares
    • 2 years ago
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    tried the formula by plugging in the numbers

  21. zaynahf
    • 2 years ago
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    Yep, its -1,-9

  22. Spartan_Of_Ares
    • 2 years ago
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    wait this ask for the minimum value not the vertex

  23. zaynahf
    • 2 years ago
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    So if thats the vertex, then what would be the minimum?

  24. Spartan_Of_Ares
    • 2 years ago
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    im lost i may have made terrible mistakes

  25. zaynahf
    • 2 years ago
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    Ok, where are you lost from?

  26. Spartan_Of_Ares
    • 2 years ago
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    everything my brain just committed suicied i made mistakes a the beging all the way to the end

  27. zaynahf
    • 2 years ago
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    for finding the vertex?

  28. Spartan_Of_Ares
    • 2 years ago
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    i... thats what i tried but i messed up completely i didnt even simplify right

  29. zaynahf
    • 2 years ago
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    where did youget up to?

  30. Spartan_Of_Ares
    • 2 years ago
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    i failed at even isolating the x terms( i've been up since 3 am) :-(

  31. zaynahf
    • 2 years ago
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    Isolate: (x^2 +2x )-8

  32. Spartan_Of_Ares
    • 2 years ago
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    ill be on later i have to go eat dinner

  33. zaynahf
    • 2 years ago
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    ok

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