To make things easier, convert the form of the function, from algebraic to root
[tex]\begin{gathered} w(x)=-(3x)^{\frac{1}{2}}-4 \\ w(x)=-\sqrt[]{3x}-4 \end{gathered}[/tex]For this function, the domain can't include negative values due to the square root. It means
[tex]D\colon\text{ x}\ge0[/tex]To define the range, evaluate the function in the lower value of the domain (which is 0)
[tex]\begin{gathered} w(0)=-\sqrt[]{3\cdot0}-4 \\ w(0)=-4 \end{gathered}[/tex]The range include all values that are less than or equal to -4
[tex]R\colon w(x)\leq-4[/tex]