#### Answer

$3 \sqrt 3$

#### Work Step by Step

$\sqrt 3 + \sqrt 12$
$\sqrt 12$ can be written as 4 x 3 because they are the factors of 12
$\sqrt 3 + \sqrt (4 \times 3)$
We see that it has the common factor of $\sqrt 3$ so we factor it out.
$\sqrt 3 ( 1 + \sqrt 4 )$
*** Square root of 4 is 2 because 2 x 2 =4
$\sqrt 3 ( 1 + 2)$
$\sqrt 3 (3)$
$3 \sqrt 3$