Question

若m^2+n^2-6n+4m+13=0,m^2-n^2=?v

Answer 1

m^2+n^2-6n+4m+13=0

m^2+4m+4+n^2-6n+9=0

(m+2)^2+(n-3)^2=0

m=-2,n=3

m^2-n^2

=(m+n)(m-n)

=-5

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