The equation of a sphere centered at (h, j, k) with radius r is
... (x -h)² +(y -j)² +(z -k)² = r²
Your sphere has center (-9, 4, 1) and radius 4, so its equation is
... (x +9)² +(y -4)² +(z -1)² = 16
This can be written in general form as
... x² + y² + z² +18x -8y -2z +82 = 0
