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Topic: re: #32
Replies: 23   Last Post: Jun 18, 2010 5:18 AM

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Roberta Silver

Posts: 188
Registered: 1/30/05
RE: #32
Posted: Jun 17, 2010 8:14 AM
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That depends on what you do first. If you square -3 and then take square root, the answer is 3. But if you take square root of -3 (i*sqrt3) and then square it, the answer is -3.

________________________________

From: owner-nyshsmath@mathforum.org on behalf of Jonathan
Sent: Wed 6/16/2010 3:15 PM
To: nyshsmath@mathforum.org
Subject: Re: #32


I belive you are correct. The square root of x squared is the absolute value of x.

for example, the square root of (-3) squared is 3, not -3.

We noticed this as we were keying the exam.

Jonathan Halabi
HS of American Studies
the Bronx


On Wed, Jun 16, 2010 at 2:48 PM, <TKENYON@crcs.wnyric.org> wrote:



I didn't teach the course this year, and most of the students had the same answer as was on the answer key, but unless it's declared "x>=0", isn't the square root of x² = absolute value of x, not just a plain x? i.e. the best answer for 32 would be -|x| sqrt(3x)
Am I missing something?


-Tom Kenyon
CRCS Mathematics/Physics
tkenyon@crcs.wnyric.org

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