1. Compute the surface area

$$
x^{2}+y^{2}+z^{2}=4(x+y+z)
$$
Answer: $48 \pi$.

Solution. If we rewrite the equation as

$$
(x-2)^{2}+(y-2)^{2}+(z-2)^{2}=12,
$$

it is easy to see that it represents a sphere, the square of whose radius is 12.

Evaluation. 10 points for the correct solution. If the surface is correctly identified as a sphere with radius $2 \sqrt{3}$, but there is an error due to not knowing the formula for the surface area of a sphere, 5 points.