Solving the Infinite Cubical Well: Griffiths QM Problem 4.2 (3rd edition) Solution FULLY EXPLAINED

In this video I will solve problem 4.2 as it appears in the 3rd edition of griffiths Introduction To Quantum Mechanics. The problem states the following:
Use separation of variables in cartesian coordinates to solve the infinite cubical well or particle in a box.
a) Find the stationary state wave functions and th ecorresponding energies
b) Call the distinct energies E1, E2, E3, in order of increasing energies. Find E1, E2, E3, E4, E5, E6. Determine the degeneracy of each of these energies.
c) What is the degeneracy of E13 and why is this case interesting?
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My name is Nick Heumann, I am a recently graduated physicist. I love to teach physics, so I decided to give YouTube a try. English is not my first language, but I hope that you can understand me well enough regardless.
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00:00 Start

[akincican]

Hi, there is an exhausted 4th-grade(5th-year) applied physics student here.
I am really enjoy learning new things and discovering new ways to approach reality but the lesson method of my professors is really discouraging. They simply think every student expert on mathematical methods of physics. Of course, I know how to solve o.d.e or what is "separation of variable method" but sometimes I can't get it why or how we used it. when this happens I can't understand anything coming after that. Most of them basically just ignore our questions or answer with "Why are you here if you don't know that", "Those are very simple things", and "This is your responsibility to figure out" kind of discouraging answers. I am taking the qm1 class for the third time because of this kind of bullshits. I am trying to explain everything to my friends just like you did(explaining every step) in this term. I admit I am not a very hard worker but mostly because of those kinds of attitudes. For example in Astrophysics II class, my professor has very good teaching methods and keeps me awake and i am one of the bests in astrophysics class. I don't know who you are but this is a great kind of teaching method for someone like me. thank you so much for this video. Thank you for "fully explained" concept
ISTANBUL' DAN SEVGİLER♥

[photon]

Super clear and helpful. Like I went to a lecture by the man, DG!

[Dreamerkhan]

Superb Nike keep it on don't stop it your work get views in future. So long term vision. But thanks for the lecture

[jubanisterist]

Hi, at 15:35 why is it that iA is positive when you have a negative sign on [ -isin(kxx)].

[berkecefe]

why does not the E_3 energy level consists of (2, 2, 1) whose sum is 9 and obviously 9 is smaller than 11 which consists of (3, 1, 1)?

[rwen]

10:19, why are we allowed to factor out X from a derivative operator?