Post Difficult Questions Here

  • 主题发起人 Elenmmare
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The Mercenary 说:
No.

What is the secondary derivative of f(x) = ((x^7+4x^5+3x^4-3x+4)(4x^3+x-7))/((x^4+3x^3-2x^2)(7x^8+4x^5+2))?

The primary derivative is
f'(x)= ((x^4+3x^3-2x^2)(7x^84x^5+2)((x^7+4x^5+3x^4-3x+4)(12x^2+1)) + (4x^3+x-7)(6x^6+20x^4+12x^3)) - (x^7+4x^5+3x^4-3x+4)(4x^3+x-7) ((x^4+3x^3-2x^2)(56x^7+20x^4)+(7x^8+4x^5+2)(4x^3+9x^2-4x))/((x^4+3x^3-2x^2)(7x^8+4x^5+2))^2

I'd solve that for you, but I'd much rather deal with my own mess. My mess being organic chemistry.
 
Ambalon 说:
@TheMerc - We all know you just smashed your keyboard with random numbers and created a huge function so that you look smart.

Actually, that would be a very simple calculus problem involving a very simple function's derivatives. I really don't want to go through and combine all the terms, and I'm wondering if there's a shortcut to get through to the secondary derivative. However, I'm not looking for an answer from you, as your posting history has made me somewhat leery of taking any answers from you, particularly on this particular math problem, as you are probably currently in Algebra 1.

ejnomad07 说:
The Mercenary 说:
No.

What is the secondary derivative of f(x) = ((x^7+4x^5+3x^4-3x+4)(4x^3+x-7))/((x^4+3x^3-2x^2)(7x^8+4x^5+2))?

The primary derivative is
f'(x)= ((x^4+3x^3-2x^2)(7x^84x^5+2)((x^7+4x^5+3x^4-3x+4)(12x^2+1)) + (4x^3+x-7)(6x^6+20x^4+12x^3)) - (x^7+4x^5+3x^4-3x+4)(4x^3+x-7) ((x^4+3x^3-2x^2)(56x^7+20x^4)+(7x^8+4x^5+2)(4x^3+9x^2-4x))/((x^4+3x^3-2x^2)(7x^8+4x^5+2))^2

I'd solve that for you, but I'd much rather deal with my own mess. My mess being organic chemistry.

I love organic chemistry! Sort of! It gets a little annoying at times and I much prefer physical chemistry!

Why would you take organic chemistry? :???:
 
Arg. You know this thread is actually supposed to be partially serious? The idea is that we're a relatively smart community, and its always fun hitting a Year 1 university professor with an explanation from a fourth Year student.
 
Elenmmare 说:
What do you about the ratio (sin i / sin r) for all angles of incidence greater than 0º?
From a denser medium to a less dense medium: There's a ratio up to a cut-off point. At that point the refracted ray has an angle of 90 degrees from the normal. Beyond that point, full internal reflection occurs.
Elenmmare 说:
Why do rays have to be shone at the center of a flat surface for proper refraction? Explain what happens when this is not done.
They don't have to. It simply simplifies things. If I shone the rays on say a globe, I'd have to do many calculations for each normal in order to find the exit ray.
 
The Mercenary 说:
No.

What is the secondary derivative of f(x) = ((x^7+4x^5+3x^4-3x+4)(4x^3+x-7))/((x^4+3x^3-2x^2)(7x^8+4x^5+2))?

The primary derivative is
f'(x)= ((x^4+3x^3-2x^2)(7x^84x^5+2)((x^7+4x^5+3x^4-3x+4)(12x^2+1)) + (4x^3+x-7)(6x^6+20x^4+12x^3)) - (x^7+4x^5+3x^4-3x+4)(4x^3+x-7) ((x^4+3x^3-2x^2)(56x^7+20x^4)+(7x^8+4x^5+2)(4x^3+9x^2-4x))/((x^4+3x^3-2x^2)(7x^8+4x^5+2))^2

I have a feeling there's an easier way to do that...
 
Tibertus 说:
The Mercenary 说:
No.

What is the secondary derivative of f(x) = ((x^7+4x^5+3x^4-3x+4)(4x^3+x-7))/((x^4+3x^3-2x^2)(7x^8+4x^5+2))?

The primary derivative is
f'(x)= ((x^4+3x^3-2x^2)(7x^84x^5+2)((x^7+4x^5+3x^4-3x+4)(12x^2+1)) + (4x^3+x-7)(6x^6+20x^4+12x^3)) - (x^7+4x^5+3x^4-3x+4)(4x^3+x-7) ((x^4+3x^3-2x^2)(56x^7+20x^4)+(7x^8+4x^5+2)(4x^3+9x^2-4x))/((x^4+3x^3-2x^2)(7x^8+4x^5+2))^2

I have a feeling there's an easier way to do that...
http://www.math.duke.edu/education/ccp/materials/diffeq/mlabtutor/mlabtut8.html
 
The Mercenary 说:
ejnomad07 说:
The Mercenary 说:
No.

What is the secondary derivative of f(x) = ((x^7+4x^5+3x^4-3x+4)(4x^3+x-7))/((x^4+3x^3-2x^2)(7x^8+4x^5+2))?

The primary derivative is
f'(x)= ((x^4+3x^3-2x^2)(7x^84x^5+2)((x^7+4x^5+3x^4-3x+4)(12x^2+1)) + (4x^3+x-7)(6x^6+20x^4+12x^3)) - (x^7+4x^5+3x^4-3x+4)(4x^3+x-7) ((x^4+3x^3-2x^2)(56x^7+20x^4)+(7x^8+4x^5+2)(4x^3+9x^2-4x))/((x^4+3x^3-2x^2)(7x^8+4x^5+2))^2

I'd solve that for you, but I'd much rather deal with my own mess. My mess being organic chemistry.

I love organic chemistry! Sort of! It gets a little annoying at times and I much prefer physical chemistry!

Why would you take organic chemistry? :???:

Check your PM's
 
Alright.

There's a beaker with a graduated cylinder stuck in it. There is a pencil inside the graduated cylinder which is filled with water. The beaker is just filled with air.

Trace the path of the rays. Beware of refraction/reflection differences.

Diagram.jpg


(Please note, my drawing sucks and all that, the black splotches are censored).

Basically we're learning about refraction and reflection. The red lines are rays, and what I *think* should happen. We're assuming these appeared out of nowhere (I know, its a stupid question for a stupid assessment). In both cases they're heading up, not down, I would have drawn on arrows but I'm lazy. What I mean to say is that they're heading into the pencil, not away from it.

Is this correct? Would they refract like I said?

Edit: Don't bother at all with the angles of incidence or refraction, that was a purely wild illustration just trying to make a point. What I really need to know is the principals, of where they would refract/reflect.
 
I can go rock climbing or I can go cliff diving.

I can’t go rock climbing nor can I go cliff diving.

Are those compound sentences? I think they are.

If a simple sentence expresses a(1) complete thought, how many "thoughts" does a compound sentence have?
 
As opposed to the morning, when I wave my hand quite quickly at night, I would always see a blur whereas in the morning I would not.
 
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