I have know idea what do to on Exercises 3-4 ....Sketch a reasonable graph of y=f(x) if it is known that f(2)=80, f(5)=40 and f(10)=25..... I dont know what kind of formula I need to use...I read all of the Introduction to the Generalized Modeling Process and found the formulas y=f(x)=ax^2+bx+c.
y=f(x)=Ab^x+c....
y=f(x)=mx+b...Do I use one of those? I am so lost!
You're not lost. You just need a little clarification on the instruction 'sketch a reasonable graph... '.
The instruction says to sketch a reasonable graph. You don't need to find a formula for the function.
If f(2) = 80 then the point (2, 80) will lie on the graph.
If f(5) = 40 then the point (5, 40) will lie on the graph.
If f(10) = 25 then the point (10, 25) will lie on the graph.
Sketch a graph containing these points. The connect them with any reasonable smooth curve, and answer the questions based on your picture.
Of course you could substitute these coordinates for x and y in the model y = a x^2 + b x + c, as we did last week, and get the formula for a parabola through these three points. Then you could find the vertex and the points 1 unit right and left, and sketch a graph based on that model. However I say this just to remind you of that process, not because I want you to go to all that trouble here.