# Thread: 2+2= 8 ; is this proof correct?

1. ## Re: 2+2= 8 ; is this proof correct?

I get that, but it doesn't explain why there is difference between "two square roots" and "the square root" appart from convention - is there a mathamatical difference.

2. ## Re: 2+2= 8 ; is this proof correct?

Originally Posted by Mytutoing
I get that, but it doesn't explain why there is difference between "two square roots" and "the square root" appart from convention - is there a mathamatical difference.
There are two square roots of 4, $\displaystyle 2~\&~-2$.
The square root of 4 is $\displaystyle \sqrt{4}=2.$.

3. ## Re: 2+2= 8 ; is this proof correct?

OK by why is this just symantics and convention or is there a mathamatical difference

4. ## Re: 2+2= 8 ; is this proof correct?

Originally Posted by Mytutoing
OK by why is this just symantics and convention or is there a mathamatical difference
There a mathematical difference: $\displaystyle \sqrt{4}\ne -2$.

5. ## Re: 2+2= 8 ; is this proof correct?

so the opperator/ symbol for taking the square root of a number is differnet to the square root of the number?!

Sorry still dont get it - the mathamatical notation seems to just be rewriting the previous MOD version in another way.

6. ## Re: 2+2= 8 ; is this proof correct?

besides if I solve the problem to find the intersect of the two lines y=5 and y=x^2 I expect two answers although I would represent the solution as [root symbol]5=x. Your argument suggests that the answer is only the positive values.

7. ## Re: 2+2= 8 ; is this proof correct?

Originally Posted by Mytutoing
so the opperator/ symbol for taking the square root of a number is differnet to the square root of the number?! Sorry still dont get it - the mathamatical seems to just be rewriting the previous MOD version in another way.
If $\displaystyle x^2=4$ then $\displaystyle x=2\text{ or }x=-2$. There are two roots of that equation.

$\displaystyle \sqrt{4}=2$ and $\displaystyle -\sqrt{4}=-2$.

If $\displaystyle |x|=2$ then $\displaystyle x=2\text{ or }x=-2$.

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# prove 2=8

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