a^2+√(b-8)+4=4a
a^2-4a+4+√(b-8)=0
(a-2)^2+√(b-8)=0
a-2=0
a=2
b-8=0
b=8
[√(ab+1)]^2
=[√(2*8+1)]^2
=[√17]^2
=17