Can this be possible?

Roraborealis · 2005-03-17 09:14:06

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?

MathsIsFun · 2005-03-17 09:23:22

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).

Roraborealis · 2005-03-17 09:26:41

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

MathsIsFun · 2005-03-17 09:42:09

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!)

Roraborealis · 2005-03-18 05:33:09

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

MathsIsFun · 2005-03-21 12:39:06

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!

Roraborealis · 2005-03-22 08:20:38

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

insomnia · 2005-03-23 23:41:30

That was weird. Any more like that?

austin81 · 2005-03-24 01:34:52

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.

Roraborealis · 2005-04-01 04:32:45

I do have another......

Mr T · 2005-04-13 04:52:30

Go on then.

konduriravali · 2005-04-14 03:20:01

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

Mr T · 2005-04-14 03:24:13

I am doing good.

Roraborealis · 2005-04-14 06:58:37

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

stewie · 2005-04-14 08:08:20

I'm actually living in Antarctica.

Mr T · 2005-04-14 08:10:15

That's because you have a thing for penguins.

stewie · 2005-04-14 08:12:42

Actually my favourite animals are ducks. *quacks*

Last edited by stewie (2005-04-14 08:13:15)

stewie · 2005-04-14 08:21:05

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

Mr T · 2005-04-14 08:24:01

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

stewie · 2005-04-14 08:26:14

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

Mr T · 2005-04-14 08:27:35

Too far Tony, too far.

stewie · 2005-04-14 08:29:01

Whatever Trevor

Mr T · 2005-04-14 08:30:59

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

stewie · 2005-04-14 08:32:08

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

Mr T · 2005-04-14 08:34:46

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

Math Is Fun Forum

#1 2005-03-17 09:14:06

Can this be possible?

#2 2005-03-17 09:23:22

Re: Can this be possible?

#3 2005-03-17 09:26:41

Re: Can this be possible?

#4 2005-03-17 09:42:09

Re: Can this be possible?

#5 2005-03-18 05:33:09

Re: Can this be possible?

#6 2005-03-21 12:39:06

Re: Can this be possible?

#7 2005-03-22 08:20:38

Re: Can this be possible?

#8 2005-03-23 23:41:30

Re: Can this be possible?

#9 2005-03-24 01:34:52

Re: Can this be possible?

#10 2005-04-01 04:32:45

Re: Can this be possible?

#11 2005-04-13 04:52:30

Re: Can this be possible?

#12 2005-04-14 03:20:01

Re: Can this be possible?

#13 2005-04-14 03:24:13

Re: Can this be possible?

#14 2005-04-14 06:58:37

Re: Can this be possible?

#15 2005-04-14 08:08:20

Re: Can this be possible?

#16 2005-04-14 08:10:15

Re: Can this be possible?

#17 2005-04-14 08:12:42

Re: Can this be possible?

#18 2005-04-14 08:21:05

Re: Can this be possible?

#19 2005-04-14 08:24:01

Re: Can this be possible?

#20 2005-04-14 08:26:14

Re: Can this be possible?

#21 2005-04-14 08:27:35

Re: Can this be possible?

#22 2005-04-14 08:29:01

Re: Can this be possible?

#23 2005-04-14 08:30:59

Re: Can this be possible?

#24 2005-04-14 08:32:08

Re: Can this be possible?

#25 2005-04-14 08:34:46

Re: Can this be possible?

Board footer