- #1

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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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- Thread starter solve
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- #1

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This is from a textbook:

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

100^1/2=10

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

Thanks.

- #2

tiny-tim

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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!

(which book?)

- #3

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hi solve!

you're right, it's wrong!

(which book?)

Thank You for the answer, tiny-tim.

As for the book, I dont wanna name it and make the otherwise excellent textbook look bad.

- #4

Ray Vickson

Science Advisor

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Thank You for the answer, tiny-tim.

As for the book, I dont wanna 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

- #5

SammyS

Staff Emeritus

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On the other hand, if the author is explaining how to solve y

y = ± √(x) = ±(x)^{1/2} for y^{2} = x

y = ±10 for y^{2} = 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.y = ±10 for y

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