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  Discussion about math, puzzles, games and fun.   Useful symbols: ÷ × ½ √ ∞ ≠ ≤ ≥ ≈ ⇒ ± ∈ Δ θ ∴ ∑ ∫ • π ƒ -¹ ² ³ °

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#27 Re: Help Me ! » number » 2015-04-29 05:12:11

Hi Faria.

Let m be the amount money and p the number of people. Then

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Now eliminate m and solve for p.

#28 Jokes » Seaplane » 2015-04-26 09:24:44

Olinguito
Replies: 5

This is a seaplane. It can land on sea.

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What's the difference between a seaplane and a blind seaplane?

#31 Re: Puzzles and Games » Jane’s cryptic crossword clues » 2015-04-24 00:47:36

#27. Sounds like funny bone (7)

#28. Sounds like bent grass (3)

#29. Set out in fact to ruin opera (4, 3, 5)

#30. English captured by Italian leader playing for advantage (5)

#31. Female mechanics (6)

#32 Re: Help Me ! » Differential equation, please help » 2015-04-23 20:16:40

First solve the homogeneous equation

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The variables are separable so should be straightforward.

Next find a particular solution to the given equation

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The general solution to the question is Ans 1 + Ans 2.

#34 Re: Help Me ! » permutation and combination » 2015-04-21 06:47:09

What about

<s><non s><non s><s><non s><s>

<s><non s><s><non s><non s><s>

#36 Re: Help Me ! » The imaginary unit (i). » 2015-04-18 03:23:04

It is not a rule. Just something I decided to put in to make things work.

Tell you what. Forget what I posted above. I didn't express myself well. Instead read Bob Bundy’s post #12. Bob has explained things much better than I did. smile

#37 Re: Help Me ! » The imaginary unit (i). » 2015-04-17 23:40:55

hussam wrote:

√4=2 ( not -2 )

but -√4=-2

so you cant write √4=-2/+2

Correct. BUT:

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Complex numbers are different.

#38 Re: Help Me ! » writing in formal language » 2015-04-17 21:41:05

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NB: If A = {1,2,3,3}, then A has three members, not four. We never count the same member in a set more than once. shame

#39 Re: Help Me ! » The imaginary unit (i). » 2015-04-17 21:04:41

So if you want to have

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one of the √(−1) is supposed to be i and the other −i. Similarly if

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one of the √(−1) is supposed to be i and the other two either both i or both −i. With a one–many relation you can't always tell.

#40 Re: Help Me ! » The imaginary unit (i). » 2015-04-17 20:50:46

hussam wrote:

√(-9)=√(-1*9)=√(-1)*√(9)=3i

That's not quite right; it should be

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Note that

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The function f(x)=√x only has the non-negative reals as domain. For negative reals, it is not a function but a one-to-many relation.

#44 Re: Jokes » Why is six afraid of seven? » 2015-04-07 19:40:56

Agnishom wrote:

That looks like bobbym

No, bobbym is much better looking than Luke Skywalker.

#46 Re: Help Me ! » Algebra 2: Quadratics » 2015-04-05 05:29:59

Now find all p such that this is equal to the given minimum value.

#47 Re: This is Cool » Formulas for the solution of Diophantine equations. » 2015-04-05 03:30:31

Hello individ. smile Hope you don't mind me contributing to your thread. I just considered diophantines of the form

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This is solvable if and only if gcd(a,b) divides c. The general solution is

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where

and X=x, Y=y is a particular solution. See this post:

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#49 Re: Help Me ! » Another kind of linear equation I never saw » 2015-04-05 03:01:23

To solve the following Diophantine equation

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Otherwise there is no solution. For example, 2x + 4y = 9 has no solution since the LHS is always even while the RHS is odd.

For example, 2x + 4y = 10  → x + 2y = 5. This step is optional but it helps by making the numbers you are working with smaller.

This can be done by trial and error. If the numbers involved are large, the Euclidean algorithm might be useful. (NB: A particular solution always exists. See following post.)

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Proof: Check first that

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Now suppose x=xʹ, y=yʹ is another solution. Then

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QED.

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