Ifxsquared = 25,ysquared = 16, andzsquared = 9 what is the greatest possible value of (x + y - z)squared?

My book says the answer is 144. Can someone please tell me how that the book got this answer?

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- Oct 13th 2009, 04:27 PMfreddyCompletely stumped on this problem!
If

**x**squared = 25,**y**squared = 16, and**z**squared = 9 what is the greatest possible value of (x + y - z)squared?

My book says the answer is 144. Can someone please tell me how that the book got this answer? - Oct 13th 2009, 04:34 PMskeeter
- Oct 13th 2009, 04:48 PMfreddyhow?
How can you make the 3 negative if its positive in the problem? You have 2 minus signs yet there is only 1 minus sign in the problem.

- Oct 13th 2009, 04:50 PMskeeter
- Oct 13th 2009, 04:55 PMgs.sh11
When you take the square root of any number such as 25 a negative can also be the solution, for example (-5)(-5) = 25, as (5)(5) = 25, so x = -5, y = -4, and because the equation is (x + y - z), z = 3, so now

$\displaystyle (-5 - 4 - 3)^2 = 144$