Question 301228
Square root requires an argument that is greater than or equal to zero. 
For example,
{{{f(x)=sqrt(x)}}}, then {{{x>=0}}}
{{{g(x)=sqrt(x-4)}}}, then {{{x-4>=0}}} or {{{x>=4}}}
{{{h(x)=sqrt(x^2+3)}}}, then x can take any value since {{{x^2+3}}} will always be positive.