Question 386843
{{{sqrt((4x)^2)}}} is easy to simplify, if you understand the relationship between squares and square roots. Squares and square roots are opposites. If a number is squared, finding the square root of it will revert back to the original number:
{{{sqrt(a^2)=a}}} 
In the question, we are asked to simplify the square root of a number (4x) which is squared. According to the aforementioned rule, the square root and square cancel each other out, leaving us with 4x.