#### Answer

x=9/16

#### Work Step by Step

Recall, in order to cancel out a square root, we square both sides of the equation. Thus, we square both sides of the equation to obtain that 16x=9. We divide both sides of the equation by 16 to isolate x and obtain: x=9/16.
We now must check our solution:
$4\sqrt{ 9/16} = 3 \\\\\ 4(3/4)=3 \\\\ 3=3$
This is true, so x=9/16.