Question

Please help! I'm stuck! Why is a third degree polynomial function with a negative leading coefficient not appropriate for modeling nonnegative real-world phenomena over a long period of time.

Answer 1

https://www.khanacademy.org/math/algebra/quadratics/features-of-quadratic-functions/v/ex3-completing-the-square

Answer 2

The link didn't help

Answer 3

What does the question even mean? What is it asking?

Answer 4

The nature of any odd polynomial function (including cubics) is to have no limit in two directions. A negative coefficient suggests it has no limit in the positive direction (y-axis) as you travel off in the negative direction (along the x-axis). It also suggests that there is no negative limit as we wander off in the positive direction. Thus, if our phenomenon is strictly positive, the negative cubic will eventually annoy us because we cannot prevent it from producing negative values.

Answer 5

So the negative values produced aren't consistent with the actual values? @tkhunny

Answer 6

nvm I'll just write the answer that I wrote above.

Answer 7

" not appropriate for modeling nonnegative real-world phenomena over a long period of time."

It's a matter of the negative cubic EVENTUALLY going negative. You can't stop it. Short-term models can be useful.

Answer 8

So what it means is that they work for short term but produce negatives in the long term

Answer 9

Oooooh! Ok! Thanks a million!