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3
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X^2 -2XY +Y^2=36 so X-Y =?

 

 

My solution:(Not so sure...)

X^2 -2XY +Y^2=(X - Y)^2

Therefore, (X - Y)^2=36 So, X-y=6

But it is also a choice question and here are the choices:

6

+-6 (Postive or negative six) (could it be?)

-6

18.

 

 

Thank you in advance!

 Apr 30, 2019
 #1
avatar+28353 
+1

The +- solution is correct.

 Apr 30, 2019
 #2
avatar
0

How ?,how could i know 

Guest Apr 30, 2019
 #3
avatar+106515 
0

If    x - y  = 6   then   (x - y)^2  = ( 6 )^2  = 36

 

If  x - y  = - 6 then  (x - y)^2  = (-6)^2  = 36

 

 

 

cool cool cool

 Apr 30, 2019

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