Math Is Fun Forum

saundo

Member

Registered: 2009-10-20

Posts: 8

proof that 2=2.82 thus that algebra has a huge fault

i have proven not that 1=2 but that 2=3.41 i am only 16 but im pretty sure there are no faults in this. what i did and expalnations on how are written below
x=2 y=2
x=y
x^2=y+x
√(x^2 )=√(y)+(x)
x=1.41+x
2=1.41+2
2=3.14
line1  x=2 y=2
line 2 therefore x=y
line 3 add x to both sides( since x=2 and 2+2 Is  the same as 2^2 it become x^2)
line 4 square root both sides of the equation
line 5 we are left with x=1.41+x because √2 is 1.41 to 2 decimal places
line 6 substitute the pro-numeral x with the its value (2) leaves us with 2=1.41+2
line 7 the answer is 2=3.41
find any faults now?

Last edited by saundo (2009-10-21 00:44:46)

dannyv

Member

Registered: 2007-09-20

Posts: 34

Re: proof that 2=2.82 thus that algebra has a huge fault

the problem is between line4 and 5. You cannot distribute the square root, i mean,

To my knowledge there is no way to decompose a square root

MathsIsFun

Administrator

Registered: 2005-01-21

Posts: 7,713

Re: proof that 2=2.82 thus that algebra has a huge fault

I removed a rude comment

Nice try, saundo, but Algebra still wins

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

saundo

Member

Registered: 2009-10-20

Posts: 8

Re: proof that 2=2.82 thus that algebra has a huge fault

the problem is between line4 and 5. You cannot distribute the square root, i mean,

To my knowledge there is no way to decompose a square root

for some reason the brackets did not come up properly

simplyjasper

Member

Registered: 2009-11-15

Posts: 24

Re: proof that 2=2.82 thus that algebra has a huge fault

3rd line itself is wrong...
If y = x,

x + y = 2x or 2y not x^2

bobbym

bumpkin

From: Bumpkinland

Registered: 2009-04-12

Posts: 109,606

Re: proof that 2=2.82 thus that algebra has a huge fault

Hi;

For x=2 and y=2 as he states in line 1:

You can say x + y = x^2.

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In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

DaveRobinsonUK

Member

Registered: 2010-04-24

Posts: 123

Re: proof that 2=2.82 thus that algebra has a huge fault

Hi Saundo

Are you using a calculator? If so are you pressing the equals sign when you add x+y or entering x then add then y
then the sqrt.

I get 1.4142136, which is the approximation of the sqrt(2) and when I then press = I get 3.4142136

The reason for this is that calculators and programming languages evaluate certain operations before others
usually following the BIDMAS rules. Since SQRT() is a division operation it would be evaluated first on the
associated number, which is 2.

If you have a bracket function, you should get 2. The correct answer should be (+/-2)

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Can feel it coming together.. Slowly but Surely

thewordalive

Member

Registered: 2010-09-27

Posts: 4

Re: proof that 2=2.82 thus that algebra has a huge fault

I removed a rude comment

Algebra still wins

algebra wins, but geometry pwns >:]