Haleyy_Bugg
The graph of which quadratic equation is shown below?
y = x^2 + 2x − 8
y = x^2 − 2x − 8
y = −x^2 − 2x + 8
y = −x^2 − 4x − 8



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Haleyy_Bugg
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Haleyy_Bugg
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@Notamathgenius

Notamathgenius
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Hmm not sure D:

MathCurious
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Does the graph of x^2 open up or down? How about x^2?
:)

cwrw238
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as its x^2 it will be open downwards like C and D

MathCurious
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f(x) + C will affect the position on the y axis. Take this fact into consideration.

cwrw238
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yup
the intercept on yaxis is when x = 0

MathCurious
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dw:1368631726428:dw
can you find the x intercepts?

MathCurious
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you should know the answer from this

Haleyy_Bugg
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I dont

MathCurious
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ok, set everything I drew above to zero, that is like saying: When is Y zero?
When Y is zero it touches the xaxis

MathCurious
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it is zero when x = 2 and when x = 4

Haleyy_Bugg
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So the answer is...?

MathCurious
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So then the answer is y = −x^2 − 2x + 8
I factored out the negative sign above.

MathCurious
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look at your graph, it's consistent with this

MathCurious
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Make sense? :)

MathCurious
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lol, just looking for someone to do your homework without effort, eh?