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AriM

  • 2 years ago

Using the quadratic function, provide the x intercepts of x^2+4x-21 Can someone just tell me what the quadratic function is..?

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  1. myininaya
    • 2 years ago
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    The quadratic function you have is x^2+4x-21 The graph will be a parabola

  2. myininaya
    • 2 years ago
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    To find the x-intercepts, set your quadratic expression(function) equal to 0. Then solve for x.

  3. AriM
    • 2 years ago
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    hmm thats what i did @myininaya and i got x = -7 and 3 but the teacher wrote -2 and use quadratic function..

  4. myininaya
    • 2 years ago
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    What is -2 suppose to be ? Your x-intercepts are correct for this quadratic function.

  5. AriM
    • 2 years ago
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    Oh im just saying he took off 2 points and wrote use quadratic function.

  6. myininaya
    • 2 years ago
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    Does he mean formula?

  7. myininaya
    • 2 years ago
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    The quadratic formula is \[x=\frac{-b \pm \sqrt{b^2-4ac}}{2a} \]

  8. AriM
    • 2 years ago
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    hmm ill try it.

  9. AriM
    • 2 years ago
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    Thanks for your help

  10. myininaya
    • 2 years ago
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    Np. Good luck.

  11. AriM
    • 2 years ago
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    tnx

  12. AriM
    • 2 years ago
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    oh if you do the quadratic function you get 3 and -7. Can you check that for me? @myininaya

  13. AriM
    • 2 years ago
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    actually, never mind. I see his point but you could have just done (x+7) (x-3) and gotten the intercepts that way.

  14. AriM
    • 2 years ago
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    do you write it as (3,0) and (-7,0) though?

  15. myininaya
    • 2 years ago
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    Yep You could have factored or used the quadratic formula.

  16. myininaya
    • 2 years ago
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    It is more proper to say the x-intercepts are (3,0) and (-7,0) I would say it is informal to say they are 3 and -7

  17. AriM
    • 2 years ago
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    Yea, i understand.

  18. myininaya
    • 2 years ago
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    Coolness.

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