1=-1

Tags: Mathematics, Math
Email this Topic • Print this Page

Read Question
Reply to All

Hi all. I found this "proof" and was just wondering if there is an error in it or not, because I couldn't find it. Any ideas?

-1/1=1/-1
sqrt(-1/1)=sqrt(1/-1)
sqrt(-1)/sqrt(1)=sqrt(1)/sqrt(-1)
i/1=1/i
i*i/1=i*1/i
i^2/1=i/i
-1=1 ?

Topic Stats
Top Replies
Link/Embed

Type: Question • Score: 0 • Views: 409 • Replies: 2

[+2] - DrewDad - 04/06/2009The error is that there are two possible values when you take a square root. sqrt(4)= 2 [i]and[/i] sqrt(4) = -2 But 2 â� -2
[+1] - fresco - 04/06/2009DrewDad is correct, The reasoning above used only the postive answer for sqrt(1). The final line should read -1=+1 or -1=-1 (where "or" is exclusive).

The error is that there are two possible values when you take a square root.

sqrt(4)= 2 and sqrt(4) = -2

But 2 ≠ -2

1 Reply

@DrewDad,

DrewDad is correct,
The reasoning above used only the postive answer for sqrt(1).
The final line should read
-1=+1 or -1=-1 (where "or" is exclusive).

0 Replies

Read Question
Reply to All

1=-1

Related Topics