What is the solution of the equation -7b = 21

1/3(x-10)=-4 solve for x with steps

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).

If y varies directly as x2 and y=6 when x=6, find the constant of variation.