first off, let's recall that a cube is just 6 squares stacked up to each other, like in the picture below. Since we know its volume, we can find how long each side is.
part A)
![\bf \textit{volume of a cube}\\\\V=x^3~~\begin{cases}x=side\\[-0.5em]\hrulefill\\V=64\end{cases}\implies 64=x^3\implies \sqrt[3]{64}=x\implies 4=x](https://tex.z-dn.net/?f=%20%5Cbf%20%5Ctextit%7Bvolume%20of%20a%20cube%7D%5C%5C%5C%5CV%3Dx%5E3~~%5Cbegin%7Bcases%7Dx%3Dside%5C%5C%5B-0.5em%5D%5Chrulefill%5C%5CV%3D64%5Cend%7Bcases%7D%5Cimplies%2064%3Dx%5E3%5Cimplies%20%5Csqrt%5B3%5D%7B64%7D%3Dx%5Cimplies%204%3Dx%20)
part B)
they have a painting with an area of 12 ft², will the painting fit flat against a side? Well, it can only fit flat if the sides of the painting are the same length or smaller than the sides of the crate, we know the crate is a 4x4x4, so are the painting's sides 4 or less?
![\bf \textit{area of a square}\\\\A=s^2~~\begin{cases}s=side\\[-0.5em]\hrulefill\\A=12\end{cases}\implies 12=s^2\implies \sqrt{12}=s\implies \stackrel{yes}{3.464\approx s}](https://tex.z-dn.net/?f=%20%5Cbf%20%5Ctextit%7Barea%20of%20a%20square%7D%5C%5C%5C%5CA%3Ds%5E2~~%5Cbegin%7Bcases%7Ds%3Dside%5C%5C%5B-0.5em%5D%5Chrulefill%5C%5CA%3D12%5Cend%7Bcases%7D%5Cimplies%2012%3Ds%5E2%5Cimplies%20%5Csqrt%7B12%7D%3Ds%5Cimplies%20%5Cstackrel%7Byes%7D%7B3.464%5Capprox%20s%7D%20)
Point is the least number of dimensions
Im sure :)
Not enough information... how much area did the student paint in 8 hours?
Answer:

Step-by-step explanation:
Given
![\int\limits {x^2\cdot e^{-4x}} \, dx = -\frac{1}{64}e^{-4x}[Ax^2 + Bx + E]C](https://tex.z-dn.net/?f=%5Cint%5Climits%20%7Bx%5E2%5Ccdot%20e%5E%7B-4x%7D%7D%20%5C%2C%20dx%20%20%3D%20-%5Cfrac%7B1%7D%7B64%7De%5E%7B-4x%7D%5BAx%5E2%20%2B%20Bx%20%2B%20E%5DC)
Required
Find 
We have:
![\int\limits {x^2\cdot e^{-4x}} \, dx = -\frac{1}{64}e^{-4x}[Ax^2 + Bx + E]C](https://tex.z-dn.net/?f=%5Cint%5Climits%20%7Bx%5E2%5Ccdot%20e%5E%7B-4x%7D%7D%20%5C%2C%20dx%20%20%3D%20-%5Cfrac%7B1%7D%7B64%7De%5E%7B-4x%7D%5BAx%5E2%20%2B%20Bx%20%2B%20E%5DC)
Using integration by parts

Where
and 
Solve for du (differentiate u)

Solve for v (integrate dv)

So, we have:




-----------------------------------------------------------------------
Solving

Integration by parts
---- 
---------- 
So:



So, we have:

![\int\limits {x^2\cdot e^{-4x}} \, dx = -\frac{x^2}{4}e^{-4x} +\frac{1}{2} [ -\frac{x}{4}e^{-4x} -\frac{1}{4}e^{-4x}]](https://tex.z-dn.net/?f=%5Cint%5Climits%20%7Bx%5E2%5Ccdot%20e%5E%7B-4x%7D%7D%20%5C%2C%20dx%20%20%3D%20-%5Cfrac%7Bx%5E2%7D%7B4%7De%5E%7B-4x%7D%20%2B%5Cfrac%7B1%7D%7B2%7D%20%5B%20-%5Cfrac%7Bx%7D%7B4%7De%5E%7B-4x%7D%20%20-%5Cfrac%7B1%7D%7B4%7De%5E%7B-4x%7D%5D)
Open bracket

Factor out 
![\int\limits {x^2\cdot e^{-4x}} \, dx = [-\frac{x^2}{4} -\frac{x}{8} -\frac{1}{8}]e^{-4x}](https://tex.z-dn.net/?f=%5Cint%5Climits%20%7Bx%5E2%5Ccdot%20e%5E%7B-4x%7D%7D%20%5C%2C%20dx%20%20%3D%20%5B-%5Cfrac%7Bx%5E2%7D%7B4%7D%20-%5Cfrac%7Bx%7D%7B8%7D%20-%5Cfrac%7B1%7D%7B8%7D%5De%5E%7B-4x%7D)
Rewrite as:
![\int\limits {x^2\cdot e^{-4x}} \, dx = [-\frac{1}{4}x^2 -\frac{1}{8}x -\frac{1}{8}]e^{-4x}](https://tex.z-dn.net/?f=%5Cint%5Climits%20%7Bx%5E2%5Ccdot%20e%5E%7B-4x%7D%7D%20%5C%2C%20dx%20%20%3D%20%5B-%5Cfrac%7B1%7D%7B4%7Dx%5E2%20-%5Cfrac%7B1%7D%7B8%7Dx%20-%5Cfrac%7B1%7D%7B8%7D%5De%5E%7B-4x%7D)
Recall that:
![\int\limits {x^2\cdot e^{-4x}} \, dx = -\frac{1}{64}e^{-4x}[Ax^2 + Bx + E]C](https://tex.z-dn.net/?f=%5Cint%5Climits%20%7Bx%5E2%5Ccdot%20e%5E%7B-4x%7D%7D%20%5C%2C%20dx%20%20%3D%20-%5Cfrac%7B1%7D%7B64%7De%5E%7B-4x%7D%5BAx%5E2%20%2B%20Bx%20%2B%20E%5DC)
![\int\limits {x^2\cdot e^{-4x}} \, dx = [-\frac{1}{64}Ax^2 -\frac{1}{64} Bx -\frac{1}{64} E]Ce^{-4x}](https://tex.z-dn.net/?f=%5Cint%5Climits%20%7Bx%5E2%5Ccdot%20e%5E%7B-4x%7D%7D%20%5C%2C%20dx%20%20%3D%20%5B-%5Cfrac%7B1%7D%7B64%7DAx%5E2%20-%5Cfrac%7B1%7D%7B64%7D%20Bx%20-%5Cfrac%7B1%7D%7B64%7D%20E%5DCe%5E%7B-4x%7D)
By comparison:



Solve A, B and C

Divide by 

Multiply by 64



Divide by 

Multiply by 64



Multiply by -64


So:

