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anonymous

  • 4 years ago

these are really hard for me.. Can someone help? The vertex of y = 9 - 8x - x2 is (-4, 25) True or False What is the vertex for the function? y = x2 - 4x - 3 Anwsers: (-1, 2) (0, -3) (1, -6) (2, -7)

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  1. anonymous
    • 4 years ago
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    I am assuming that when you say x2 you mean \[x^2\]

  2. anonymous
    • 4 years ago
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    yes

  3. anonymous
    • 4 years ago
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    (2,-7)

  4. anonymous
    • 4 years ago
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    Can you help me with the previous ones i posted?

  5. anonymous
    • 4 years ago
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    To do this, we find the axis of symmetry, which (in standard form of ax^2 + bx + c) is x = -b/a which in this case is -8, then we plug that into x to get the y-value of the vertex, 9, so the vertex is (-8, 9)

  6. anonymous
    • 4 years ago
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    so false

  7. anonymous
    • 4 years ago
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    can you help me with these two? What are the values of a, b, and c in the function? List them in order with commas, such as 1,-2,3. y = -2x2 + 5x - 4 What is the vertex for the function? (You will want to find the axis of symmetry first.) Write as an ordered pair, leaving no spaces, such as (1,-4). y = -3x2 + 6x

  8. anonymous
    • 4 years ago
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    look at the standard form i posted above.

  9. anonymous
    • 4 years ago
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    i dnt get it

  10. anonymous
    • 4 years ago
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    \[y = ax^2 + bx + c\]

  11. anonymous
    • 4 years ago
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    ??

  12. anonymous
    • 4 years ago
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    now you can do the first one, then look how I found the axis of symmetry above, -b/a, in this case on the second question -6/-3 = 2

  13. anonymous
    • 4 years ago
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    Ok, What about the first one?

  14. anonymous
    • 4 years ago
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    \[y = ax^2 + bx + c \] this is the standard form of a quadratic equation, quadratic means that the highest exponent is 2 such as \[x^2\]

  15. anonymous
    • 4 years ago
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    OK,

  16. anonymous
    • 4 years ago
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    find the coefficients of x^2 and x in their respective places relative to a and b, c is the constant number on the end (-4)

  17. anonymous
    • 4 years ago
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    i got it :)

  18. anonymous
    • 4 years ago
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    One more? Thanks so much for your help! Which coefficient in the function tells us that the parabola for the function will point downward? y = -2x2 + 5x - 4

  19. anonymous
    • 4 years ago
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    Anwsers: -2 5 -4

  20. anonymous
    • 4 years ago
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    the direction of the parabola depends on whether the coefficient of the x^2 term is positive or negative. If it is positive such as 5x^2 it will point up, but -3x^2 would point down. In this case -2 is the coefficient which means it points downward

  21. anonymous
    • 4 years ago
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    ohhh kk!!

  22. anonymous
    • 4 years ago
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    HOW DO I FIGURE THIS OUT \[6\sqrt{2} - 3\sqrt{2}\]

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