Question

(2005-k)平方+(k-2006)平方=2

Answer 1

(2005-k)^2+(k-2006)^2=2

令m=2005-k,n=k-2006

m^2+n^2=2

m+n=-1

mn=1/2[(m+n)^2-(m^2+n^2)]

=1/2(1-2)

=-1/2