Melody

Yes I agree

I'd just write it as

\(f(x)=x(x+22)^3\)

I have already answered this question.  Guest, you do not need your homework done for you.

I told you I am happy to talk to you about it. 

Don't be so lazy.

CPhill, how did you calculate that 100/1+9e^(-0.4(15)) is approx equal to 978?

CPhill did not say   100/    he said   1000/

1000/(1+9*e^(-0.4*15)) = 978.1780512369621114

Yes I saw the question. I asked you for your thoughts.

I am not going to give you a full answer but I am happy to discuss it with you.

Hint:

Think about the number of ways in which the family can have 0,1, or 2 children.

Now that I have started this question please noone answer over the top of me.

Thanks Heureka :)

What is your question?  I mean what is the problme that you have with this question.

Please be specific. What are your thoughts on it?  

It depends what form your equation is in.

If it is of the form

\((x-h)^2=4a(y-k)\)

Then the vertex is  (h,k) 

the focal length is |a|

If a is positive then it is concave up, if a is negative then it is concave down.

The focus is (h,k+a)  the axis of symmetry is x=h   and the directrix is   y=k-a

The definition of a parabola is the locus of all points equidistant from a line called the directrix and a point called the focus.

Give the directrix and the focus you can determine the equation of the parabola using locus (which is a fun things to do when you get used to the method)

What would you use the directrix for ? ... not sure what this question is after but if you google it the answer may become clear :/