Find max/min within what we've been taught?

1. Feb 15, 2005

ktpr2

Hi,

I have the function $$0.1x^3 - 3x$$ and I would like to find its local maxima and minima within the domain of [-10,10]. The problem is I don't think we've been taught a way yet; I'm currently in Calculus I and just before derivatives. Is there a way within my current knowledge to find the fraction representing the max and min of this function within the above domain?

2. Feb 15, 2005

vsage

I would think that the local max and min could be approximated by taking the midpoint x value between roots. Edit: Have you been taught limit notation yet?

3. Feb 15, 2005

dextercioby

Can't u use a computer & graph it...?

Daniel.

4. Feb 15, 2005

ktpr2

Yeah we've been taught limit notation. And we can probably just give the value 3.1622... but I'm trying to be as thorough as possible.

We have roots
$$\sqrt{1.2}/1.2 and 0$$
The midpoint isn't the max/min cause the function isn't linear (i think thats why).

5. Feb 15, 2005

dextercioby

Unfortunately u can find the exact (x,y) values or the extrem through calculus.Approximate values can be achived by plotting...It has 3 roots,BTW

Daniel.

6. Feb 15, 2005

vsage

If you know limit notation I think you can cheat and use the definition of a derivative.