Math Is Fun Forum
You are not logged in.
- Topics: Active | Unanswered
Pages: 1
#1 Help Me ! » Question about Euler-lagranges equation » 2010-05-15 00:37:18
- xXxEmZyxXx
- Replies: 0
so ive been revising my lecture note and ive found a subject which is slightly confusing me
I have the following integral
we have the euler equation:
which gives us two equations
does anyone know how to get to these answers. i've tried to solve it but i think i've gone wrong with my differentiation
#2 Re: Help Me ! » new integration variable » 2010-02-22 03:55:26
ahh i understand that now must have missed a step.
suppose i want to change the denominator to
im assuming i use the same method though using a different integration variable delta as
now i've tried doing it like this and it gets a bit messy and im finding it hard to calculate the dx's does anyone have a suggestion for a different integration variable?
#3 Help Me ! » new integration variable » 2010-02-20 07:43:08
- xXxEmZyxXx
- Replies: 3
Hey im trying to understand my lecture notes, i have the following method of integration which is confusing me
here the new integration variable delta is used as
so we have
this i understand but then my notes say
which is where i get confused. does anyone know how to calculate this x-1?? any help would be much appreciated
#4 Help Me ! » functions » 2007-10-30 22:29:11
- xXxEmZyxXx
- Replies: 4
g: B->A such that g(f(a))=a for all aEA
h:B->A such that f(h(b)=b for all bEB
show that g(b)=h(b) for all bEB
#5 Re: Help Me ! » injective function » 2007-10-30 08:53:38
the answer should not refer to the inverse of f since it may not exist
#6 Help Me ! » surjective function » 2007-10-30 08:38:47
- xXxEmZyxXx
- Replies: 2
let A B be sets
f:A->B
suppose there is a function h:B->A with the property that f(h(b)=b for all bEB
show that f has to be surjective
please help will be much appreciated!!!
#7 Help Me ! » injective function » 2007-10-30 08:23:41
- xXxEmZyxXx
- Replies: 4
let a b be sets
f:A->B
suppose there is a function g: B->A with the property that g(f(a))=a for all aEA. show that f has to be injective
please help!!!
#8 Help Me ! » functions » 2007-10-30 06:58:28
- xXxEmZyxXx
- Replies: 1
x/(1+x^2) is this surjective injective or both how can you tell???
#9 Re: Help Me ! » functions » 2007-10-30 06:21:46
thanks but what properties of sine/cosine did you use to get the values of x???
#10 Help Me ! » polar form » 2007-10-29 01:59:06
- xXxEmZyxXx
- Replies: 2
find solution ZEC in polar form for the equation Z^6=1
please help!:D
#11 Help Me ! » functions » 2007-10-29 01:53:53
- xXxEmZyxXx
- Replies: 1
let a,b be sets
suppose there is a function g:B->A with the property that g(f(a))=a for all aEA. show that f has to be surjective
please help!!!
#12 Help Me ! » functions » 2007-10-25 07:11:40
- xXxEmZyxXx
- Replies: 2
F(x)=5sin(2x)-2cosx
is this funtion R->R
injective, surjective, or both anyone know and can show me how to determine for future references
#13 Help Me ! » integration » 2007-10-23 08:57:32
- xXxEmZyxXx
- Replies: 1
does anyone know if this is the correct method of integration??
integrate sin(Pi*x)
i got as a result (-cos(Pi*x))/(Pi)
anyone know if this is right/wrong???
Pi= 3.141592654
#14 Help Me ! » integration » 2007-10-23 08:54:35
- xXxEmZyxXx
- Replies: 1
please help me integrate
cos(^3)xsin(^3)x
#15 Help Me ! » arctan function » 2007-10-22 06:13:20
- xXxEmZyxXx
- Replies: 3
intergrate tan^(-1)dx
#16 Help Me ! » integration by parts » 2007-10-22 06:12:31
- xXxEmZyxXx
- Replies: 1
intergrate e^(2x) cos(3x) dx
anyone???
#17 Help Me ! » integration » 2007-10-22 06:11:18
- xXxEmZyxXx
- Replies: 7
intergrate tanh(2x+1)dx
please help!!!
#18 Help Me ! » greatest common divisors » 2007-10-15 02:05:48
- xXxEmZyxXx
- Replies: 6
find the greatest common divisor of 2241 and 1411. check your answer by factorizing these numbers into a product of primes
#19 Help Me ! » Proofs!! » 2007-10-15 01:49:11
- xXxEmZyxXx
- Replies: 2
Help me please 
1) Prove that there do not exist natural numbers a, b with (a/b)^2=5
2) where does the proof go wrong if you try to use the same arguement to prove the (incorrect) statement that there do not exist natural numbers a, b with (a/b)^2=4?
Any help much appreciated!!!
#20 Help Me ! » Axioms for real numbers proofs!!! » 2007-10-15 01:43:51
- xXxEmZyxXx
- Replies: 1
hey if anyone could help me with the two following proofs by using the axioms for real numbers it would be very much appreicated!!!
1) Suppose c ER has the property that ca=a, for some non-zero aER. prove that c=1
2) Suppose x, y ,z are real numbers and Z<0 and X<Y. prove that XZ>YZ
thanks in advance 
Pages: 1