Answer
$2(x^2+120/x)$, $x\gt 0$
Work Step by Step
We know that the volume is $60$. Thus,
$V=x^2h=60$
and hence $h=60/x^2$
We plug this value into the surface area formula to get:
$S(x)=2(x^2+xh+xh)=2(x^2+2xh)=2(x^2+2x(60/x^2))=2(x^2+120/x)$
where, $x\gt 0$
