PDA

View Full Version : 5,000 Credits for an answer to this

rzr
04-1-2009, 02:21 PM
I was sitting in my algebra II class and we had to create a problem like this:

x x x x = y

Between the x's can only be /, *, -, or + opertaors. Here's mine:

4 4 4 4 = 19

Problem is, the ink smudged where I wrote the answer down, so I forgot it. We (meaning my whole class and teacher) spent the whole time trying to figure it out. In the end they determined that I was playing an April Fool's prank on them. I wasn't. 5k to whoever figures it out first. Unless you love me and do it for free.

Xx{Midnight}xX
04-1-2009, 02:25 PM
1 + 2 - 3 * 4 = 0

bluguerrilla
04-1-2009, 02:29 PM
Sure there aren't 5 4s?

Because if so 4*4+4-4/4 = 19 but otherwise, meh.

travman301
04-1-2009, 02:33 PM
4^2 = 16 + 4 = 20 - (4/4) = 19

bluguerrilla
04-1-2009, 02:38 PM
That's four operations and identical to what I posted except much less correct.

4^2 =/= 19. ;)

rzr
04-1-2009, 02:38 PM
Only four four's. And trav...?

bluguerrilla
04-1-2009, 02:42 PM
Pretty sure it's impossible.

4*4+4/4 = 17

4*4+4+4 = 24

Can't get anything in between, I don't think.

e: didn't do anything exhaustive though, just punched some numbers into my calculator. I don't know how to go about solving stuff like this without writing a program or something. :)

rzr
04-1-2009, 02:50 PM
Me either, man! It's driving my nuts. Especially since I wrote it by sitting there and just putting it 3 random operators.

travman301
04-1-2009, 03:14 PM
That's four operations and identical to what I posted except much less correct.

4^2 =/= 19. ;)

What are you talking about? What I posted was correct. Technically I guess I was using 5 fours. But its impossible any other way.

Mabye I was being unclear in what i was saying. :)

4²+4-(4/4)=19

That's what I was trying to say. ^_^

If you count the exponent as an operation then you can do it like that.

dean_machine
04-1-2009, 03:15 PM
I think you made a mistake the first time you thought it was correct.

Redorigami
04-1-2009, 03:19 PM
Were you even right in the first place?

bluguerrilla
04-1-2009, 03:21 PM
What are you talking about? What I posted was correct. Technically I guess I was using 5 fours. But its impossible any other way.

Mabye I was being unclear in what i was saying. :)

4²+4-(4/4)=19

That's what I was trying to say. ^_^

If you count the exponent as an operation then you can do it like that.

4^2=4*4... Basically you cheated.

And you can't write numbers with equal signs between them like that unless all of the expressions are actually equal, which yours aren't. It's just not right.

I understand what you meant but as mathematics, it's wrong.

It's like writing a bunch of sentences with no punctuation all in a row.

e: And I don't think he _was_ right in the first place. But I'm not about to go through all of the operations to prove it.

travman301
04-1-2009, 03:24 PM
4^2=4*4... Basically you cheated.

And you can't write numbers with equal signs between them like that unless all of the expressions are actually equal, which yours aren't. It's just not right.

I understand what you meant but as mathematics, it's wrong.

It's like writing a bunch of sentences with no punctuation all in a row.

e: And I don't think he _was_ right in the first place. But I'm not about to go through all of the operations to prove it.

Heh, I got what you were trying to say. :)

I realize I was wrong. But it's also impossible what he's asking.

Dark_Chrysalis
04-1-2009, 03:33 PM
If the stipulation is that ANY operation can be used, the solution is found thus:

4!-4-(4/4)=19

Not sure if this will count, but it is correct... in fact, I think its the only solution

kommisar[os]
04-1-2009, 03:41 PM
4+4+4+4 = 19-1

CobaltWire
04-1-2009, 05:04 PM
4 4 4 4 = 19? That's doesn't seem possible, without cheating

Redorigami
04-1-2009, 05:05 PM
;3031805']4+4+4+4 = 19-1

coraleaterlinda
04-1-2009, 05:18 PM
i cant figure this out for the life of me. i dont think its possible.

Archelos
04-1-2009, 05:21 PM
April Fool's.

TC_Halogen
04-1-2009, 05:38 PM
4/4-4x4 = -15

This solution makes me think that there is an answer to it. Do you remember having any negatives of some sort? I mean, I know it isn't the answer, but I'm trying to think of something using the operators you have. I'm not sure it's possible. =l

Eeumi
04-1-2009, 05:57 PM
If the stipulation is that ANY operation can be used, the solution is found thus:

4!-4-(4/4)=19

Not sure if this will count, but it is correct... in fact, I think its the only solution

I think this is the only way

clarinet89
04-1-2009, 07:10 PM
by only using 4s?

rzr
04-1-2009, 07:25 PM
I swear it worked. I think it went plus or times then division or subtraction then division or subtraction.

Redorigami
04-1-2009, 07:52 PM
You know neither 4 plus 4 nor 4 times 4 gives you a number higher than 19 and dividing and subtracting from there would accomplish absolutely nothing correct?

Unless you somehow made 4x4 into 20 because you were dumb and that would have yielded a correct answer.

knuckles2224
04-1-2009, 07:59 PM
You said the answer got smudged out? I find that hard to believe? Is the answer April fools? or impossible?

devonin
04-1-2009, 09:07 PM
If it's either of those things, you shouldn't have made that thread here.

rzr
04-1-2009, 09:26 PM
It's not April Fool's. And I the calculator didn't malfunction.

devonin
04-1-2009, 09:35 PM
Using only + - * and / (And thus, no brackets, exponents etc, and taking each to mean and only mean addition, subtraction, multiplication and division?

And not doing something moronic like using the / to go over the = to make "does not equal" ?

lumphoboextreme
04-1-2009, 09:42 PM
haha. yeahhh... you can't get an odd number from all 4's. it's impossible

ninjaKIWI
04-1-2009, 09:51 PM
haha. yeahhh... you can't get an odd number from all 4's. it's impossible

4*4+4/4 = 17

Idiot.

foilman8805
04-1-2009, 09:53 PM
wrecked

foilman8805
04-1-2009, 09:55 PM
Also, the only plausible explanation I can give for getting an answer of 19 is an order of operations error that calculators can be prone to if the user neglects to use parentheses (or uses them incorrectly).

Ground_Breaker
04-1-2009, 10:09 PM
I'm pretty sure it's impossible with x=4.

The only way you can get an odd number is with what NinjaKIWI posted, which requires you to divide 4/4 to get 1, and that's not going to leave you with enough to reach 19. Two even numbers, when added, subtracted, multiplied, or divided (except for x/x) will always equal another even number, so you made an error somewhere.

rzr
04-1-2009, 10:14 PM
What error, Erich?

foilman8805
04-1-2009, 10:16 PM
Order of operations. I just said it was merely a possibility. It may not effect it at all. I really don't think it can be done.

AC1speakerbox
04-1-2009, 10:19 PM
This problem > Me
(serously though, it can't be done)

emerald000
04-1-2009, 10:23 PM
Well, I ran a little script trying every possible combination of operators (and brackets while at it) and there was no 19 in there. So it is impossible in normal mathematical logic.

AC1speakerbox
04-1-2009, 10:24 PM
haha. yeahhh... you can't get an odd number from all 4's. it's impossible

I sense stupid

devonin
04-1-2009, 11:14 PM
Well, I ran a little script trying every possible combination of operators (and brackets while at it) and there was no 19 in there. So it is impossible in normal mathematical logic.

So rzr...

bluguerrilla
04-2-2009, 12:11 PM
Wrecked, give the man (emerald) 5k credits, me as well because I called it first and someone else because you punched the numbers into the calculator wrong and deserve to be out 15k credits. :)

leonid
04-3-2009, 04:37 AM
~-(4*(4+4/4)) = ~-20 = 19

~ is bitwise complement operator. :D

Also, 4.4*4.4 = 19.36 = about 19.

Yee Yee-kun
04-3-2009, 06:08 AM
1+1-1x1=1

Blue Bird
04-3-2009, 07:44 AM
I could go code a program that...

4 + 4 + 4 + 4 = ?
4 - 4 + 4 + 4 = ?
4 * 4 + 4 + 4 = ?
4 / 4 + 4 + 4 = ?
4 + 4 - 4 + 4 = ?
...
4 / 4 / 4 / 4 = ?

Then sort out all the answers in numerical order, and see what we get. =P

I'll do it for 5k. *cough*

EDIT:
Well, I ran a little script trying every possible combination of operators (and brackets while at it) and there was no 19 in there. So it is impossible in normal mathematical logic.

Damn I really... I should read the entire thread next time, and not just stop in the middle of the 2nd. =.= My bad.

Redorigami
04-3-2009, 10:18 AM
I still think he said 4x4 was 20 somewhere when he did it.
I've seen people make that mistake before and it's the only way to do it with his suggested order of increasing the first one and decreasing the second two.

rzr
04-3-2009, 12:22 PM
If emerald proves it's impossible then the credits go to the first person who said it's impossible. I feel bad though. I swear it said 19. Maybe it really was 17. Thanks, guys.