# Squaring on both sides

• Dec 6th 2013, 08:19 PM
AaPa
Squaring on both sides
a+b=±6(sqrt(ab))

squaring on both sides

a^2 + b^2=34ab

a/b=17±12(sqrt(2))

But the answer is only 17+12(sqrt(2)). I know the extra root is because I squared on both sides.But how do we tell which is the right one?

Thanks.
• Dec 6th 2013, 08:49 PM
romsek
Re: Squaring on both sides
Quote:

Originally Posted by AaPa
a+b=±6(sqrt(ab))

squaring on both sides

a^2 + b^2=34ab

a/b=17±12(sqrt(2))

But the answer is only 17+12(sqrt(2)). I know the extra root is because I squared on both sides.But how do we tell which is the right one?

Thanks.

they both work. I don't know that one is any more "right" than the other.
• Dec 6th 2013, 08:54 PM
itrealcon
Re: Squaring on both sides
interesting question..
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• Dec 6th 2013, 09:50 PM
AaPa
Re: Squaring on both sides
thanks I realized my mistake.