[Visirale]

Ok, for IB we have this simple paper thing that we have to do, and it's supposed to show our ability to explain abstract concepts at a simple level...

I've got it all figured out except for this one simple part, and I've tried it over and over and can't get it to work out. I can get it equal, but not the same...

(x) (2x) ((400 - 2x^2)/(3x)) = (4/3)(x)(200-x^2)

In words...

base of a container equals x cm long, 2x cm wide. Height equals four hundred - two x squared all over 3 x. I have to show that the volume of this container equals four thirds x times 200 - x squared.

See if you can help me any :-\

[SccHarpGirl]

I got it. Give me five minutes and I'll scan in my solution as it's easier to show on paper than on the computer

[SccHarpGirl]

hope this helps and that I didn't make any mistakes. That'd be embarassing

[Visirale]

Thank you very very much. Amazing how even in pre-calc, basic albebra can still come back in reincarnated super forms... :P

[SccHarpGirl]

yeah, I screwed up majorly on my calc 2 final exam because of basic algebra...haha...it never dies.

[jbm222]

there's a MUCH simpler solution....

(x)(2x)(400 - 2x^2)/(3x)

canceling x's (say first one and the one in the "3x") and moving the 3 gives:

(2/3)(x)(400-2x^2)

then bring out a factor of 2 from the (400-2x^2):

(2/3)(x)(2)(200-x^2)

(4/3)(x)(200-x^2)

HarpGirl's solution (800x/3 - (4x^3)/3 ) would generally be considered the simplest form of the expression

just in case you wanted to know.

what's interesting is that this function only gives positvie volume when x is negative... plot it and see for yourself.

[jbm222]

yeah... um... i think you've got your word description mixed up... that doesn't make any sense... those values for the box deminsions don't really describe any real situation that i can think of