SOLUTION: If x = 2015, y = 2014 and z = 2013, then the value of x² + y² +z² – xy – yz – zx is

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Question 1040358: If x = 2015, y = 2014 and z = 2013, then the value of
x² + y² +z² – xy – yz – zx is
Answer by ikleyn(52776)   (Show Source): You can put this solution on YOUR website!
.
If x = 2015, y = 2014 and z = 2013, then the value of
x² + y² +z² – xy – yz – zx is
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 

    = 

=  = 

=  = 

= 2015*1 + 2014*1 + 2013*(-2) =  2015 + 2014 - 2*2013 = (2015-2013) + (2014-2013) = 3.

The right and more effective question would be "calculate without a calculator".


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