What is -12x-5(-8)=40

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).

The equation x2 – 1x – 90 = 0 has solutions {a, b}. what is a + b?

What three-dimensional solid have 6 rectangular faces, 2 equal bases that are not rectangles and 18 edges