Question

determine the domain f(x)=sq root sign over 7-x

Answer 1

\[f(x)=\sqrt{7-x}\]

Answer 2

\[f(x)=\sqrt{7-x}\] you cannot take the square root of a negative number so solve
\[7-x\geq 0\]
get
\[7\geq x\] is your domain

Answer 3

as an interval it is
\[(-\infty,7]\]