Answer
$\sqrt {9\cdot 3}-\sqrt {4\cdot 3}=3\sqrt 3-2\sqrt 3 =\sqrt 3$.
Work Step by Step
The given expression is
$=\sqrt {27}-\sqrt {12}$
Factor:
$=\sqrt {9 \cdot 3}-\sqrt {4 \cdot 3}$
Use $\sqrt {a^2} = a$
$=3\sqrt { 3}-2\sqrt {3}$
Simplify.
$=\sqrt 3$.
