Question

X^2+Y^2-4X-6Y+13=0

Answer 1

X^2+Y^2-4X-6Y+13=0

(X-2)^2+(Y-3)^2=0

两个实数平方和为0,那么这两个数都为0

X-2=0,Y-3=0

X=2,Y=3

Y^2-X^2=3^2-2^2=9-4=5