a²-2a+b²+6b+10=0
a²-2a+1+b²+6b+9=0
(a-1)²+(b+3)²=0
a-1=0 b+3=0
a=1 b=-3
1/(1/a+1/b)
=ab/(a+b)
=1*(-3)/(1-3)
=3/2 ( 2分之3)