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

solve

1. The problem statement, all variables and given/known data

This is from a textbook:

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

2. Relevant equations
3. The attempt at a solution

100^1/2=10

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

Thanks.

tiny-tim

hi solve!

Quote by solve

This is from a textbook:

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

2. Relevant equations
3. 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?)

solve

Quote by tiny-tim

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.

Ray Vickson

Quote by solve

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

SammyS

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.

Similar discussions for: Y=X^1/2 is the same as Y=+/-sqrt(X) ??
Thread	Forum	Replies
Prove that the limit of sin(sqrt(x+1))-sin(sqrt(x-1)) at infinity doesn't exist	Calculus & Beyond Homework	10
Prove series is divergent (sqrt(n+1) - sqrt(n))/sqrt(n)	Calculus & Beyond Homework	5
Iterative square root? sqrt(2+sqrt(2+sqrt(...	General Math	6
Is there a way to show that sqrt(2)+sqrt(3)+sqrt(5) is algebraic over Q?	General Math	4
Proof that sqrt(6)-sqrt(2)-sqrt(3) is irrational	General Math	10

solve	Y=X^1/2 is the same as Y=+/-sqrt(X) ?? 1. The problem statement, all variables and given/known data This is from a textbook: Y=X^1/2 is the same as Y=+/-sqrt(X) 2. Relevant equations 3. The attempt at a solution 100^1/2=10 How is 100^1/2=-10 also true? Thanks.

SammyS Mentor	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.