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# Square-rooting question watch

1. Hello there,

If I have the answer to a question that is a square root, do I have to use the plus minus sign?

Question example:

Rearrange the formula to make r the subject of it.

A= (pi*r^2)/2

Do I have to make the answer +/- sqrt((2A)/pi), or is just sqrt((2A)/pi) enough?

A.T.
2. Just sqrt, I'd say. I'm pretty sure you just +/- if you're writing it as an unsquare rooted (don't know the actual term) number. So like either sqrt9 or +/-3. If that makes sense,
3. In the marking scheme they put brackets (+/-) on the answer. What does that mean?
4. (Original post by Atham)
In the marking scheme they put brackets (+/-) on the answer. What does that mean?
It means they will not deduct a mark if you include the +/- sign.

Don't though. Think about the physical situation. You really don't want a negative radius.
5. (Original post by AshenSun)
Just sqrt, I'd say. I'm pretty sure you just +/- if you're writing it as an unsquare rooted (don't know the actual term) number. So like either sqrt9 or +/-3. If that makes sense,
That isn't correct.

6. (Original post by Mr M)
It means they will not deduct a mark if you include the +/- sign.

Don't though. Think about the physical situation. You really don't want a negative radius.
Yeah, that is why I left it positive.
7. (Original post by Atham)
Yeah, that is why I left it positive.
You did the right thing then.

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