I am having trouble with the following question.

Two functions are defined as $\displaystyle f(x)=-x^2$ $\displaystyle g(x)=sqrt{x}$

a) Find the smallest possible value of a given that the domain of the function h, where $\displaystyle h(x)=(f+g)(x)$, is a is less than or equal to x and 2 is greater than or equal to x