Math Is Fun Forum
  Discussion about math, puzzles, games and fun.   Useful symbols: √ ∞ ≠ ≤ ≥ ≈ ⇒ ∈ Δ θ ∴ ∑ ∫ π -

Login

Username

Password

Not registered yet?

#1 2005-03-18 08:14:06

Roraborealis
Super Member

Offline

Can this be possible?

My maths tutor told me this, and I'm very curious about it. Every time I try to follow it, I get confused. It apparently proves that 1=0.
x=1.
Multiply both sides by x and you get
2x=x
Take away 1 from each side which becomes
2x-1=x-1
This can also be expressed as
(x+1)+(x-1)=x-1
Divide each side by x-1 and the answer is:
x+1=1
From this, you can see that x=0. But at the beginning I said that x=1. It has therefore been proved that 1=0.

Is this a trick?


School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?
 

#2 2005-03-18 08:23:22

MathsIsFun
Administrator

Offline

Re: Can this be possible?

I know there IS something like this, but right at the start your tutor's proof says "2x=x" which can't be true (unless x=0 when lots of silly things become true).


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman
 

#3 2005-03-18 08:26:41

Roraborealis
Super Member

Offline

Re: Can this be possible?

Aha. I knew it was a trick when I couldn't understand it!


School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?
 

#4 2005-03-18 08:42:09

MathsIsFun
Administrator

Offline

Re: Can this be possible?

But there is this one:

Start with: a = b

Then add (-b+b) to the left hand side (this is OK because you are adding 0:      a - b + b = b

Now divide both sides by (a-b) and we have:

        a - b + b   =    b
        ________     _____
          (a-b)          (a-b)

Reducing the left side:
             
        1 +     b     =     b
               ____       _____
               (a-b)       (a-b)

Then subtract b/(a-b) from both sides and you have:

                1=0


(Mwuuhahhah - maniacal laughter!)


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman
 

#5 2005-03-19 04:33:09

Roraborealis
Super Member

Offline

Re: Can this be possible?

Hahahahahaha! It's humorous to see that algebra can prove weird things!


School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?
 

#6 2005-03-22 11:39:06

MathsIsFun
Administrator

Offline

Re: Can this be possible?

But before we all think that Algebra is odd, there IS a mistake in the proof.

When I first saw it I was confooosed, and someone had to point out to me that because we said that a=b, then (a-b) must equal zero. When you start multiplying or dividing by zero, all hell breaks loose, and you start to get weird looking proofs.

So watch out for those in your proofs!


"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman
 

#7 2005-03-23 07:20:38

Roraborealis
Super Member

Offline

Re: Can this be possible?

Oh.........never mind. At least it was funny.


School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?
 

#8 2005-03-24 22:41:30

insomnia
Real Member

Offline

Re: Can this be possible?

That was weird. Any more like that?


Friends are angels who lift our feet when our own wings have trouble remembering how to fly
 

#9 2005-03-25 00:34:52

austin81
Member

Offline

Re: Can this be possible?

It's not a trick! There's wrong division in the course of dividing both sides of the equation (x+1)+(x-1)=x-1 by x-1.

 

#10 2005-04-02 02:32:45

Roraborealis
Super Member

Offline

Re: Can this be possible?

I do have another......


School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?
 

#11 2005-04-14 02:52:30

Mr T
Super Member

Offline

Re: Can this be possible?

Go on then.


I come back stronger than a powered-up Pac-Man big_smile
I bought a large popcorn @ the cinema the other day, it was pretty big...some might even say it was "large
cool Fatboy Slim is a Legend cool
 

#12 2005-04-15 01:20:01

konduriravali
Member

Offline

Re: Can this be possible?

Hi,
How   are  you  doing?
By  the  way   where   do   you   stay.
Send  me  mail  ,go  to   HELPME   and   then    you  go  to
Maths  by  ravali.
byeeeee,
ravali

 

#13 2005-04-15 01:24:13

Mr T
Super Member

Offline

Re: Can this be possible?

I am doing good.


I come back stronger than a powered-up Pac-Man big_smile
I bought a large popcorn @ the cinema the other day, it was pretty big...some might even say it was "large
cool Fatboy Slim is a Legend cool
 

#14 2005-04-15 04:58:37

Roraborealis
Super Member

Offline

Re: Can this be possible?

I think most of us here are in the UK (well, I think, anyway).


School is practice for the future. Practice makes perfect. But - nobody's perfect, so why practice?
 

#15 2005-04-15 06:08:20

stewie
Power Member

Offline

Re: Can this be possible?

I'm actually living in Antarctica. cool


HAPPY HAPPY, JOY JOY  big_smile
cool Fatboy Slim is the band of the 90s, thats if you want to call it a band because its really a one man name cool
 

#16 2005-04-15 06:10:15

Mr T
Super Member

Offline

Re: Can this be possible?

That's because you have a thing for penguins.


I come back stronger than a powered-up Pac-Man big_smile
I bought a large popcorn @ the cinema the other day, it was pretty big...some might even say it was "large
cool Fatboy Slim is a Legend cool
 

#17 2005-04-15 06:12:42

stewie
Power Member

Offline

Re: Can this be possible?

Actually my favourite animals are ducks. *quacks* tongue

Last edited by stewie (2005-04-15 06:13:15)


HAPPY HAPPY, JOY JOY  big_smile
cool Fatboy Slim is the band of the 90s, thats if you want to call it a band because its really a one man name cool
 

#18 2005-04-15 06:21:05

stewie
Power Member

Offline

Re: Can this be possible?

I don't care. I know what I like and that's white white white.


HAPPY HAPPY, JOY JOY  big_smile
cool Fatboy Slim is the band of the 90s, thats if you want to call it a band because its really a one man name cool
 

#19 2005-04-15 06:24:01

Mr T
Super Member

Offline

Re: Can this be possible?

It's good for ye, top models eat it.


I come back stronger than a powered-up Pac-Man big_smile
I bought a large popcorn @ the cinema the other day, it was pretty big...some might even say it was "large
cool Fatboy Slim is a Legend cool
 

#20 2005-04-15 06:26:14

stewie
Power Member

Offline

Re: Can this be possible?

Give us grease that makes us obese....oh how we love to eat junk! big_smile


HAPPY HAPPY, JOY JOY  big_smile
cool Fatboy Slim is the band of the 90s, thats if you want to call it a band because its really a one man name cool
 

#21 2005-04-15 06:27:35

Mr T
Super Member

Offline

Re: Can this be possible?

Too far Tony, too far.


I come back stronger than a powered-up Pac-Man big_smile
I bought a large popcorn @ the cinema the other day, it was pretty big...some might even say it was "large
cool Fatboy Slim is a Legend cool
 

#22 2005-04-15 06:29:01

stewie
Power Member

Offline

Re: Can this be possible?

Whatever Trevor


HAPPY HAPPY, JOY JOY  big_smile
cool Fatboy Slim is the band of the 90s, thats if you want to call it a band because its really a one man name cool
 

#23 2005-04-15 06:30:59

Mr T
Super Member

Offline

Re: Can this be possible?

Yet again, my phrase, you stole it, check earlier topics again.


I come back stronger than a powered-up Pac-Man big_smile
I bought a large popcorn @ the cinema the other day, it was pretty big...some might even say it was "large
cool Fatboy Slim is a Legend cool
 

#24 2005-04-15 06:32:08

stewie
Power Member

Offline

Re: Can this be possible?

Actually no, you heard me saying it and put it in here before me! mad


HAPPY HAPPY, JOY JOY  big_smile
cool Fatboy Slim is the band of the 90s, thats if you want to call it a band because its really a one man name cool
 

#25 2005-04-15 06:34:46

Mr T
Super Member

Offline

Re: Can this be possible?

You came up with drinkin bleach, I'll give you that but I did not steal whatever Trevor off you foo'


I come back stronger than a powered-up Pac-Man big_smile
I bought a large popcorn @ the cinema the other day, it was pretty big...some might even say it was "large
cool Fatboy Slim is a Legend cool
 

Board footer

Powered by FluxBB