Help please.

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).

Evaluate the expression for the given value of the variable 7a - 4a for a =8

Simplify 15(x - 4)(x -1)-3(x + 4)(x - 1) with steps