#### Answer

$8+2\sqrt{15}$

#### Work Step by Step

$(\sqrt3+\sqrt5)^2$=
$(\sqrt{3}+\sqrt5)(\sqrt{3}+\sqrt5)$
Use the FOIL method to multiply the binomial.
Multiply the First terms, the Outside terms, the Inside terms, and the Last terms.
$(\sqrt{3}\times\sqrt{3})+(\sqrt3\times\sqrt5)+(\sqrt3\times\sqrt5)+(\sqrt5\times(\sqrt5))$
Simplify.
$3+\sqrt{15}+\sqrt15+5$
Combine like terms/like radicals.
$8+2\sqrt{15}$