Y=X^1/2 is the same as Y=+/-sqrt(X) ?

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Homework Help Overview

The discussion revolves around the equivalence of the expressions Y=X^1/2 and Y=+/-sqrt(X) as presented in a textbook. Participants are examining the implications of this equivalence, particularly in the context of solving equations involving square roots.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are questioning the validity of the textbook's claim that Y=X^1/2 is the same as Y=+/-sqrt(X), particularly in relation to specific numerical examples like 100^1/2.

Discussion Status

Some participants express skepticism about the textbook's assertion, suggesting it may be incorrect. Others point out that the context of solving equations could influence the interpretation of the expressions, indicating a nuanced discussion without a clear consensus.

Contextual Notes

There is mention of a potential error in the textbook, and participants are considering whether the author provided sufficient detail in the explanation. The original poster's reluctance to name the textbook suggests a concern about the implications of critiquing published material.

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Y=X^1/2 is the same as Y=+/-sqrt(X) ??

Homework Statement




This is from a textbook:

Y=X^1/2 is the same as Y=+/-sqrt(X)

Homework Equations


The Attempt at a Solution



100^1/2=10

How is 100^1/2=-10 also true?

Thanks.
 
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hi solve! :wink:
solve said:
This is from a textbook:

Y=X^1/2 is the same as Y=+/-sqrt(X)

Homework Equations


The Attempt at a Solution



100^1/2=10

How is 100^1/2=-10 also true?

Thanks.

you're right, it's wrong! :smile:

(which book?)
 


tiny-tim said:
hi solve! :wink:


you're right, it's wrong! :smile:

(which book?)


Thank You for the answer, tiny-tim.

As for the book, I don't want to name it and make the otherwise excellent textbook look bad.
 


solve said:
Thank You for the answer, tiny-tim.

As for the book, I don't want to name it and make the otherwise excellent textbook look bad.

Actually, you would be doing the author a favor by telling us the name and author of the book; that way, professionals could write to him/her about the error, so it could be fixed in subsequent editions.

RGV
 


On the other hand, if the author is explaining how to solve y2 = x, for y, or solve y2 = 100 for y, then the answers are:
y = ± √(x) = ±(x)1/2 for y2 = x

y = ±10 for y2 = 100​
If this is the case you have only told us part of what the textbook was claiming, although the author may have also left a few details out of her/his explanation.
 

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