a²+b²-a+4b+4.25=0
(a²-a+0.25)+(b²+4b+4)=0
(a-0.5)²+(b+2)²=0
a-0.5=0 b+2=0
a=0.5 b=-2
(a-1/2)^2+(b+2)^2=0
a=1/2,b=-2
解:a^2+b^2-a+4b+4.25=a^2-a+0.25+b^2+4b+4=(a-0.5)^2+(b+2)^2
因为(a-0.5)^2≥0,
(b+2)^2≥0,
所以a-0.5=0,
b+2=0,
a=0.5,b=-2.
a=1/2 ,b=2 配完全平方:(a-1/2)^2+(b-2)^2=0
a²+b²-a+4b+4.25
=a²-a+0.25+b²+4b+4
=(a-0.5)²+(b+2)²
=0
a=0.5
b=-2