Question 852341
Revenue is the money that comes in.
Cost is the money that goes out.
Profit is the difference {{{Revenue-Cost}}}.

(c)
Find the maximum point, or the vertex.  The function value there is the maximum revenue.  You could use the general solution for a quadratic equation to help find the maximum point, which will be in the middle of the horizontal axis intercepts.  You could also Complete the Square to put the revenue function into standard for and read the vertex directly from the standard form.  Already plenty of resources exist for understanding this, including <a href="http://www.algebra.com/tutors/Completing-the-Square-Using-Pictures.lesson?content_action=show_dev">what is completing the square?</a>   and  <a href="http://www.algebra.com/tutors/Completing-the-Square-to-Solve-General-Quadratic-Equation.lesson?content_action=show_dev">solve quadratic by completing the square</a>

(d)
Look at the constant term in the cost function.  THAT is the fixed cost.  This is the amount not dependant on q.

(e)
If you understand d, then you understand this one.

(f)
Too obvious.  What's the degree of the function?

(g)
Break-even when when cost value equals revenue value; for profit of zero.


People look at symbols, read descriptions, and then try to make things more complicated than they really are.  We do not know why any revenue might fit a quadratic model or why a cost might fit a linear model, or why either might fit whatever model were found; but when we have the model, we can just use it.