a^2*b^2+a^2+b^2+16=10ab
a^2*b^2-8ab+16+a^2+b^2-2ab=0
(ab-4)^2+(a-b)^2=0
所以 ab-4=0,a-b=0
解得:a=b=2或a=b=-2
a^2+b^2=8