m²-4m+5
=m²-4m+4+1
=(m-2)²+1≥1
∴不论m取何值,代数式m²-4m+5的值总不小于1
x²+y²-4X+6y+13=0
(x²-4x+4)+(y²+6y+9)=0
(x-2)²+(y+3)²=0
∴{{x-2=0
y+3=0
即x=2, y=-3
m²-4m+5
=m²-4m+4+1
=(m-2)²+1≥1
∴不论m取何值,代数式m²-4m+5的值总不小于1
x²+y²-4X+6y+13=0
(x²-4x+4)+(y²+6y+9)=0
(x-2)²+(y+3)²=0
∴{{x-2=0
y+3=0
即x=2, y=-3