AriM
Using the quadratic function, provide the x intercepts of x^2+4x21
Can someone just tell me what the quadratic function is..?



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myininaya
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The quadratic function you have is x^2+4x21
The graph will be a parabola

myininaya
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To find the xintercepts, set your quadratic expression(function) equal to 0.
Then solve for x.

AriM
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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..

myininaya
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What is 2 suppose to be ?
Your xintercepts are correct for this quadratic function.

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

myininaya
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Does he mean formula?

myininaya
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The quadratic formula is
\[x=\frac{b \pm \sqrt{b^24ac}}{2a} \]

AriM
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hmm ill try it.

AriM
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Thanks for your help

myininaya
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Np. Good luck.

AriM
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tnx

AriM
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oh if you do the quadratic function you get 3 and 7. Can you check that for me? @myininaya

AriM
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actually, never mind. I see his point but you could have just done (x+7) (x3) and gotten the intercepts that way.

AriM
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do you write it as (3,0) and (7,0) though?

myininaya
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Yep
You could have factored or used the quadratic formula.

myininaya
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It is more proper to say the xintercepts are (3,0) and (7,0)
I would say it is informal to say they are 3 and 7

AriM
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Yea, i understand.

myininaya
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Coolness.