#### Answer

$\sqrt 42pqr$

#### Work Step by Step

The product rule for radicals tells us that $\sqrt[n] a\times\sqrt[n] b=\sqrt[n] ab$ (when $\sqrt[n] a$ and $\sqrt[n] b$ are real numbers and $n$ is a natural number). That is, the product of two nth roots is the nth root of the product.
Therefore, $\sqrt 14\times\sqrt 3pqr=\sqrt (14\times 3pqr)=\sqrt 42pqr$.