What is 29.99 after sales tax of 6.25

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).

Use the function f(x) is graphed below. the graph of the function to find, f(6). -2 -1 1 2

Is this a polynomial function? i need to know asap