Answer:
Step-by-step explanation:
x = # of small boxes and y = # of large boxes
6x + 22y = 320
x = y + 2
this would be ur system of equations
0x1=0
1x2=2
2x3=6
3x4=12
4x5=20
First of all, we can observe that

So the expression becomes

This means that the expression is defined for every 
Now, since the denominator is always positive (when it exists), the fraction can only be positive if the denominator is also positive: we must ask

Since we can't accept 3 as an answer, the actual solution set is
![(-\infty,-2] \cup [2,3) \cup (3,\infty)](https://tex.z-dn.net/?f=%28-%5Cinfty%2C-2%5D%20%5Ccup%20%5B2%2C3%29%20%5Ccup%20%283%2C%5Cinfty%29)
V=x(8-2x)(10-2x) or expanded
V=x(4x^2-36x+80)
V=4x^3-36x^2+80x
...
If you were to graph the above equation for V(x) you will see a maximum point where the "y" value is maximized, but be careful as V will increase without bound at values of x that are not part of the domain, ie, in this case x<8/2, x<4 to have any meaning...The proper domain of this function is:
x=(0,4), Mathematically finding this point quickly is by differentiating it with respect to x...
dV/dx=12x^2-72x+80, The maximum volume will occur when dV/dx=0 and the x value is within the correct domain...
12x^2-72x+80=0 (using the quadratic formula for ease)
x=(72±√1344)/24, and since x<4
x≈1.472in (to the nearest one thousandth of an inch)