Graphing quadratic functions

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juliemariefort

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f(x) = x^2 + 6x - 16.

I need to find:

Vertex__________

y-intercept__________

x-intercepts__________

Axis of symmetry (equation required)__________

Then, I need to graph it. I don't even know where to start!
 
juliemariefort said:
f(x) = x^2 + 6x - 16.

I need to find:

Vertex__________

y-intercept__________

x-intercepts__________

Axis of symmetry (equation required)__________

Then, I need to graph it. I don't even know where to start!
Click to expand...

This is an equation of a parabola.

So re-write in the form:

f(x) = (x-h)[sup:2ms6rx52]2[/sup:2ms6rx52] + k

Then your vertex is (h,k)

for x intercept(s), you need to find x at y=0 , or you need to solve for 'x' from 0 = x^2 + 6x -16

similarly for y-intercept, you need to find y at x=0

your axisof symmetry will be the vertical line passing through the vertex.

Please show your work, indicating where you are stuck - so that we know where to begin to help you.
 
juliemariefort said:
I don't even know where to start!
Click to expand...
Hmm... They were supposed to have covered the various topics listed before assigning homework on them! :shock:

To make up for this deficiency, you'll need to study some online lessons:

. . . . .Google results for "complete square vertex"

. . . . .Google results for "x y intercepts"

. . . . .Google results for "parabola axis symmetry"

. . . . .Google results for "graphing quadratic"

Once you have learned the basic terms and techniques related to the necessary background material, please attempt the exercise. If you get stuck, you will then be able to reply with a clear listing of your work and reasoning so far.

Thank you! :D
 
That's what I get for taking an online course at a community college taught by someone that already has a full-time job.

For f(x) = x^2 + 6x - 16

I figured out that the:
vertex is (-3, 25)
y-intercept is (0, -16)
x-intercepts are (2, 0) (-8,0)
Axis of symmetry: x=3

Is this correct?
 
juliemariefort said:
Is this correct?
Click to expand...

Hmmm. It's difficult for me to say. From your postings at this site, I think you are having trouble proofreading your own typing.

I see two mistakes in your results, but they may be more typographical errors.

The value of f(-3) is wrong.

The equation for the axis of symmetry is wrong.
 
juliemariefort said:
That's what I get for taking an online course at a community college taught by someone that already has a full-time job.

For f(x) = x^2 + 6x - 16

I figured out that the:
vertex is (-3, -25)
y-intercept is (0, -16)
x-intercepts are (2, 0) (-8,0)
Axis of symmetry: x = -3

Now those are correct....

Is this correct?
Click to expand...
 
Thank you. I'm still very new to this, so I make mistakes. I will be more careful from now on. I appreciate your help.
 
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