# daniton

Senior Members

151

1. ## What does "find the dx/dy of (eq inside) for x>0" mean?

No,the function ln(x) is not defined for x<=0
2. ## What if our creator aka GOD is dead ?

First why you post it in earth science thread. second as you said you're NUTS!! but to be honest I liked your ,what to call it ...... interesting!
3. ## set theory - doubt about reasoning

By the way you should be more careful on the question it is a little tricky. Any way you did great. Can I ask what grade are you in?
4. ## Fermat,s Last Theorem

By the way I have tried to prove Fermat s Last Theorem from Pythagorean theorem.I didn't finish it completely just need more taught just not use such complicated number theory ...... my idea is very simple I try to find integers which satisfy Pythagorean theorem using general formula the prove that are not perfect square. what do you say??
5. ## need a simple understanding

I don't know this whole thing but in High school I used equivalent mass to calculate Normality.There is also sth called number of equivalents.Sorry I couldn't help but if you need sth like this or equivalent mass I used in solution chemistry I can help you.
6. ## set theory - doubt about reasoning

When you try to find "sth only" for example A only you should subtract any intersection of any thing with A from A but those relation should be them and them only ,those intersection must have no intersection. if in system of A,B,C relations AnC AnB AnBnC AnC only = AnC - AnBnC AnB only = AnB - AnBnC AnBnC only = AnBnC when you subtract all these from A you get : A only = A - AnC - AnB + AnBnC try it fresh with this.
7. ## CIE exam

Thanks a lot for your help!!!! I use extremepapers too but I didn't find organized test papers.
8. ## set theory - doubt about reasoning

Oh!! my bad correct it with (AnC)u(BnC) don't you know about the distributive laws of sets. for more see: http://en.m.wikipedia.org/wiki/Algebra_of_sets
9. ## how electromagnets work?

I think asad118 is trying to say moving electrons in metal atom assumed in the whole metal.
10. ## How do I find the max min of this function?

Why don't you just second derivative test.It's easy and quick.
11. ## set theory - doubt about reasoning

you raise good example.You can see that you add AnBnC: d three times when you mix A,B,C than you subtract it three times on AnB,AnC,BnC which you can understand you removed AnBnC from the calculation at all. So, you have to bring it back by adding it specifically. BTW you can proof it for general case just do this AUBUC = (AUB)UC = AUB +C - (AuB)nC (AuB)nC= (AnB)u(BnC) =AnB+BnC-(AnBnBnC) AnBnBnC=AnBnC so AUBUC=A+B+C- AnB - AnC- BnC+ AnBnC I think you understand the sign change there. Just give it some thought!!
12. ## Electrostatics - Can someone tell me where I went wrong?

Electrostatic force doesn't cancels the gravitational force(and it couldn't cancel ) the tension does.
13. ## can any one tell me how this came

For constant pressure and temperature yeah. just use PV=nRT V=kn simple right.
14. ## A Carnot engine operates between reservoirs at 20 and 200°C. If 10 kW of power is produced, the rejected heat rate is nearest

This forum is actually to help anyone despite there scientific knowledge and in this thread (homework help) we help, but we don't do. In my previous post I try to show you how it is done. Just try it I'm sure you can get it. If you follow it you should get 16.3
15. ## A Carnot engine operates between reservoirs at 20 and 200°C. If 10 kW of power is produced, the rejected heat rate is nearest

to the answer may be or approximately.... any way you find the efficiency and then the power delivered if it was 100% efficient in the end it's a matter of subtraction with the given power.
16. ## I need help solving inverse trigonometric problem.

try this Cos(z+y)=Cos(z)Cos(y)-Sin(z)Sin(y) => z+y= Cos⁻¹ [Cos(z)Cos(y)-Sin(z)Sin(y)] using this: the expression becomes this by little rearranging Cos⁻¹[(2/ √13 )*x - (3/ (√13)) *√(1 -x²)] Cos(z)=? Cos(y)=? try the rest. I think that helps!
17. ## CIE exam

yeah that would be nice if you know physics too. I'm taking the exam in November. Do you have Facebook or twitter account? for more! thanks in advance.
18. ## CIE exam

the one thing that bother me is that I couldn't find any revision guide.I'm taking maths and physics and one which I didn't decide for sure may be pure mathematics but I couldn't find any.
19. ## set theory - doubt about reasoning

The reason why you have to add AnBnC is because you subtracted it two times not once one in AuB two in (AuB)uC since it is a part of both(try to imagine it in circle or something like that).So, you have to make correction so you did ,you add it. in general : AuBuC=A+B+C - AnB - BnC - AnC + AnBnC
20. ## orbital equation of motion

I may not know well about those complicated things may be when I get in to astrophysics but i got this link which may add fuel to this hot discussion http://www.sciencedaily.com/releases/2013/05/130529191041.htm?utm_source=feedburner&utm_medium=email&utm_campaign=Feed%3A+sciencedaily%2Fmatter_energy%2Fphysics+%28ScienceDaily%3A+Matter+%26+Energy+News+--+Physics%29 BTW I really like the discussion!!!
21. ## set theory - exercise

you're absolutely correct. you are asked (O U S)' == Universe - (O U S) which you answered!!!!
22. ## expanding c=-a*sin(α)+b*cos(α)

why are you expanding? what are you trying to find? I didn't understand any of what you did may be it's beyond me:-)
23. ## can I convert the unit ?

Any time!!!!!
24. ## Why are resonance hybrid supposed to be considered to be stable?

I think he is saying why the hybrid is more stable than the resonance structure.for example benzene's structure is intermediate between the other resonance structures and stable. but why? I know the fact since high school but I didn't read any thing why delocalization stabilize it. When I google it I found this link check it out... this might help. http://academic.reed.edu/chemistry/roco/resonance/geometry.html
25. ## can I convert the unit ?

That is not necessary and depends on what you want to get , but if you want you can.The basic thing behind unit convention is that use SI units not be confused and more importantly agreement of units And another thing kilo mole is not common to use its better just to change KPa into Pa.
×