Final answer:
The vector equation for the line through point P(1, -5, -5) and parallel to vector v(-1, 2, 1) is r = (1, -5, -5) + t(-1, 2, 1).
Step-by-step explanation:
To find a vector equation for the line through point P(1, -5, -5) and parallel to vector v(-1, 2, 1), we can use the point-slope form of a line equation. The equation is given by r = r0 + tv, where r is the position vector, r0 is the given point, t is a scalar, and v is the direction vector.
Substituting the given values, the vector equation becomes:
r = (1, -5, -5) + t(-1, 2, 1)
This is the vector equation for the line through point P and parallel to vector v.