t=√b/a+√a/b>0
t²=b/a+a/b+2√(b/a*a/b)
=(b²+a²)/ab+2
=[(a+b)²-2ab]/ab+2
=[36-16]/8+2
=2.5+2
=4.5
∴t=√b/a+√a/b=√4.5=3√2/2