a²-3a+b²-½b+37/16=0
(a-3/2)²+(b-1/4)²=0
则:必有:
a-3/2=0
b-1/4=0
解得:a=3/2;b=1/4
a-4根号b
=3/2-4×1/2
=3/2-2
=-1/2
即-2分之1