\[\sqrt{14q}\times 2\sqrt{4q}\]
Multiplying the terms under the square root signs gives:
\[2\sqrt{56q ^{2}}\]
4 is one of the factors of 56. 4 and q^2can be taken out from under the square root sign (taking the square roots of both) giving:
\[2\times 2\times q \sqrt{14}\]