Find the values if the variables

How to determine whether two known pairs of points are on the same line.

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).

Ineed with angles and the measure of them i have abc a is 65 and b is (3x-10) and c is (2x) find the value of x