Find the value of k so that the lines (x - 3)/(3k + 1) = (y + 6)/2 = (z + 3)/2k and quantity (x + 7)/3 = (y + 8)/-2k = (z + 9)/-3 are perpendicular.

Answer 1

the dot product must be zero. That is,
(3k+1)(3) + 2(-2k) + (2k)(-3) = 0
k = 3