How can you identify a resonable domain and range for a word problem? also what would be the format to write it?

Find the gradient of f(x, y,z)equals=left parenthesis x squared plus y squared plus z squared right parenthesis superscript negative 1 divided by 2 baseline plus ln left parenthesis x right parenthesis x2+y2+z2−1/2+ln(xyz) at the point left parenthesis negative 2 comma 1 comma negative 2 right parenthesis(−2,1,−2).

For how answer my question this will be the last question can you answer in math subject

Identify an equation in point slope form for the line perpendicular to y=3x+5 that passes through (4,-1)