a√(a/b)+b√(b/a)
=a√a/√b+b√b/√a
=a^2/√(ab)+b^2/√(ab)
=(a^2+b^2)/√(ab)
=[(a+b)^2-2ab]/√(ab)
将a+b=-8,ab=8代入
=[(-8)^2-2*8]/√8
=48/2√2
=12√2