QUICK QUESTION: Minimizing Restrictions

[banfill_89]

Homework Statement

Question: a box with a square base and no top must have a volume of 10,000cm^3. if the smallest dimensions in any direction is 5cm, the determine the dimensions of the box that minimize the amount of material used.

Homework Equations

V=x^2&y
SA=x^2+4xy
(isolate for y using given volume in V equation to obtain y=10,000/x^2)

The Attempt at a Solution

SA=x^2+4x(10,000/x^2)

when solved...x=27.1
y= 13.6I have an answer on what the dimensions are, but what do i use as my limitations besides what my x values are. I know i have to use x>or=5...for some reason i can never figure these limitations/restrictions out...

 

[jhicks]

"must have a volume of 10,000cm^3" Sounds like a restriction to me.