# Thread: Need help solving this equation (may be factoring)?

1. ## Need help solving this equation (may be factoring)?

Hi, in math class, we were assigned a challenge problem that has to do with finding the volume of a box. My function is:

f(x) = 4x3 - 88x2 + 480x

I found that the maximum value of this function is 768 (the maximum volume), but I want to know how to solve for x. This is what I have:
768 = 4x3 - 88x2 + 480x
192 = x3 - 22x2 + 120x

How would I continue to solve for x?

2. ## Re: Need help solving this equation (may be factoring)?

How did you get your answer of 768? It should actually be about 774 by the way.

3. ## Re: Need help solving this equation (may be factoring)?

Originally Posted by Flurite
Hi, in math class, we were assigned a challenge problem that has to do with finding the volume of a box. My function is:

f(x) = 4x3 - 88x2 + 480x

I found that the maximum value of this function is 768 (the maximum volume), but I want to know how to solve for x. This is what I have:
768 = 4x3 - 88x2 + 480x
192 = x3 - 22x2 + 120x

How would I continue to solve for x?
how did you find that the maximum volume is 768?

I get approximately 774.

4. ## Re: Need help solving this equation (may be factoring)?

I used my graphing calculator, but then I just realized that decimals are involved too. All I need is the x value and I can't find that in my table.

5. ## Re: Need help solving this equation (may be factoring)?

graph the volume and find the maximum ... it will give you the max volume (y-value) and x-value where that maximum occurs.

6. ## Re: Need help solving this equation (may be factoring)?

Found out how to change the maximum and minimum values to shift where the graph is showing. Thanks all!