Math Riddle

[AceHart]

> (8/(x^2))/(5-(2/x)) <-- Don't feel like simplifying.

8 / ( (5 - 2 / x) * x^2 )
Not really "simpler" though


> I'm not positive about these, but I think they're right. (Did them quickly.)

They are correct.


> Also, if there were doubles of the books, then there would be less

" Yes, we have seen this already, therefore just imagine that this arrangement does not exist "

 

[Amfidamant]

Allright, two nice riddles for you, brain-nuggets

Easy riddles:
1)How to show (Not sure if that's how should I write) 56 with six fives?

2)How to show number 1000 without any zero's?

3)What will be the next number in this row of numbers:
1 4 8 13 19


Harder one

Two people are going from point A to point B which are 2km afar. One by bicycle, the other - by a motorcicle.
Every minute the Bicycle driving man drives 500 meters less than the motorcycle man.
For the Bicycle-man, it takes two hours longer to drive to the point B, than to the motorcycle man.

Again, sorry for spelling. I'm still sleeping.

 

[Tonks]

1) X = 5+5+5+5+5+31
2) X = 1111-111
3) (N+6-2=X) 23?

-I hate problems like the distance one, but what is the question? It looks like you gave us the answer?-

 

[Amfidamant]

Oh, Right.

Whats the speed of both of them?

Actually...

Only the second is correct.

Come on, give a better shot.

 

[Tonks]

Oh, Right.

Whats the speed of both of them?

Actually...

Only the second is correct.

Come on, give a better shot.

Psh.. I had a half day at school today.. You expect me to THINK?
Also, #1 fits your specifications.
Eh.. screw #3.. I'm going to sleep.

 

[Amfidamant]

With ONLY six fives, if that makes it better

When you get the answer, you understand how simple it is.

 

[Mullit]

#3 is 26

 

[Amfidamant]

Correct.

1 (+3) 4 (+4) 8 (+5) 13 (+6) 19 (+7) 26

Only two more to go

 

[AceHart]

#3 is, obviously, 42. What else?

Based on this easy function:
f(x) = ( -587520 * x^5 - 9020160 * x^4 - 53049600 * x^3 + 149817600 * x^2 - 220078080 * x + 89994240) / -24883200

x = 1 => f(x) = 1
x = 2 => f(x) = 4
x = 3 => f(x) = 8
x = 4 => f(x) = 13
x = 5 => f(x) = 19
x = 6 => f(x) = 42




EDIT:

Btw, (5+5) * 5 + 5/5 + 5 = 10 * 5 + 1 + 5 = 50 + 6 = 56

 

[Amfidamant]

That's Nice ^^

what about this row of numbers?

2 6 22 86

 

[AceHart]

I guess you expect 342.

Though, 42 is equally valid

 

[Amfidamant]

By that same formula again?

And yes, I expected 342

as for the 56, there is an easier way (Like you would take one )

55 + 55/55

How about this row? No way of getting 42!

A1z B2y C3x D4w

(Not hard to answer thou )

And how about the

Two people are going from point A to point B which are 2km afar. One by bicycle, the other - by a motorcicle.
Every minute the Bicycle driving man drives 500 meters less than the motorcycle man.
For the Bicycle-man, it takes two hours longer to drive to the point B, than to the motorcycle man.
What's their speed?

 

[Mullit]

>x = 1 => f(x) = 1
x = 2 => f(x) = 4
x = 3 => f(x) = 8
x = 4 => f(x) = 13
x = 5 => f(x) = 19
x = 6 => f(x) = 42


why didnt you just write f(1), f(2), f(3) etc??


>A1z B2y C3x D4w E5v

 

[Amfidamant]

Correct

One last riddle of mine left currently (But I have an almost infinite resource of them.. my brain! )

Anyway, anyone else wants to share their riddles?

 

[AceHart]

> By that same formula again?

Almost.
f(x) = (-62784 * x^4 + 665280 * x^3 - 2364480 * x^2 + 3412800 * x - 1581696) / 34560

f(1)...f(5) give, in order, 2, 6, 22, 86, 42.

 

[Amfidamant]

Can you tell me why is it always 42?
Is it somewhat magical number?

 

[Weyrling]

42 is the meaning of life, the universe, and everything. As according the the Hitchhikers Guide to the Galaxy.

 

[Chocobo]

2 6 22 86

If (6-2), (22-6), and (86-22) = xy Then y=(86-22)/(22-6)
6-2=4
22-6=16
86-22=64

Because (6-2), (22-6), and (86-22) = xy, y=64/16=4
4*4=16
16*4=64
64*4=256



What about this stupid riddle to solve :

C = (n!)/(p!(n-p)!)

C has for power p, and for information, n.

 p
C
 n

Find a formula so solve this using developpements.


And this :

x^y = ???

Find a way using "e" (e1) to get this to work using only "e1".

Answer for this in white :

C^n = e^(n ln C) if I remember.

 

[Mr Zero]

What number shall replace the questionmark? (In the thrid box)

  2    4
3        7
  6    2

  1    3
9        9
  7    4

  4    8
1        3
  8    [B]?[/B]

Hmm...

 

[Tom Jones]

>1)How to show (Not sure if that's how should I write) 56 with six fives?
The logical solution would be 5+5*5+5+(5/5).