Math Is Fun Forum
You are not logged in.
- Topics: Active | Unanswered
#126 Puzzles and Games » How many » 2008-08-21 07:05:09
- tony123
- Replies: 1
A group of 20 people pay a total of £20 to see an exhibition. The admission price is £3 for 2 adults, £2 for seniors and 50p for children. How many adults, seniors and children are in the group?
#127 Puzzles and Games » Find all positive integers » 2008-08-20 09:36:46
- tony123
- Replies: 1
Find all positive integers
and which satisfy.
#128 Puzzles and Games » Solve in natural numbers: » 2008-08-15 19:59:25
- tony123
- Replies: 3
Solve in natural numbers:
#129 Re: Puzzles and Games » all prime numbers » 2008-08-14 10:49:54
very nice
#130 Puzzles and Games » all prime numbers » 2008-08-13 12:03:09
- tony123
- Replies: 4
Find all prime numbers
and all positive integers
such that
#131 Re: Help Me ! » I am useless at proving inequalities » 2008-08-11 00:02:12
The inequality is equivalent to
By AM-GM Inequality,
.
It is obvious that
,so we are done!
#132 Re: Help Me ! » I am useless at proving inequalities » 2008-08-10 22:26:17
Set
. With some calculations, we get the new problem accompanying the condition
By AM-GM, we have the simple inequality: in order to imply the important result
( which is what we want!)
#133 Help Me ! » conditions » 2008-08-08 20:34:04
- tony123
- Replies: 1
#134 Puzzles and Games » Find all pairs » 2008-08-07 09:07:46
- tony123
- Replies: 6
Find all pairs of natural numbers (x,y) for which
#135 Help Me ! » solve in R » 2008-08-05 14:07:15
- tony123
- Replies: 5
solve in R
#136 Help Me ! » Find four numbers » 2008-08-04 13:26:31
- tony123
- Replies: 4
Find four numbers A, B, C, D
so that 0 < A< B < C < D and
.
#137 Puzzles and Games » integ » 2008-08-02 08:45:09
- tony123
- Replies: 1
find
#138 Re: Exercises » Without use of any calculator » 2008-07-24 23:58:11
but from where you get these
#139 Exercises » Find the minimum » 2008-07-23 19:59:40
- tony123
- Replies: 0
Find the minimum of the expression
if
are real numbers satisfying the conditions:a> 1
and
.#140 Puzzles and Games » Find all pairs » 2008-07-23 05:14:48
- tony123
- Replies: 3
Find all pairs of positive integers
such that
is a primeand
is a perfect square#141 Re: Puzzles and Games » Determine » 2008-07-23 05:08:00
thank you ZHero
nice work
and
Since a^2-b^2 +c^2-d^2 is odd, one of the primes a, b, c and d must be 2,
and in view of a > 3b > 6c > 12d we must have d = 2.
#142 Re: Exercises » Find all functions » 2008-07-23 04:40:36
thank you jane
but i think The only solution of function is f(x) = x,
what can be easily checked.
#143 Puzzles and Games » Proofs Without Words » 2008-07-21 20:10:04
- tony123
- Replies: 0
problem
if
, then
.
solution
#144 Puzzles and Games » Determine » 2008-07-21 05:00:48
- tony123
- Replies: 4
Let
and be prime numberssuch that
and
Determine all possible values of
.
#145 Exercises » Determine all real numbers » 2008-07-21 04:44:34
- tony123
- Replies: 1
Determine all real numbers
that satisfy the following system ofequations.
#146 Exercises » Imo 2008 » 2008-07-20 21:59:03
- tony123
- Replies: 3
49th International Mathematical Olympiad
http://www.imo-2008.es/index.html
http://www.imo-2008.es/examenes/eng.pdf
#147 Exercises » Find all functions » 2008-07-20 18:38:52
- tony123
- Replies: 4
Find all functions f: (0,∞)------ (0,∞) such that
f(f(f(x))) + 4f(f(x)) + f(x) = 6x .
#148 Exercises » Without use of any calculator » 2008-07-18 09:47:54
- tony123
- Replies: 7
Without use of any calculator, determine
#149 Exercises » maximum value » 2008-07-18 06:39:21
- tony123
- Replies: 3
Determine the maximum value of
if
#150 Exercises » Which is larger » 2008-07-18 06:34:30
- tony123
- Replies: 12
Which is larger,
or
and how