Question: Find the value of k if the vectors A = (1, k, 2) and B = (2, 3, 4) are perpendicular.
Options:
Correct Answer: 1
Solution:
A · B = 1*2 + k*3 + 2*4 = 0. Thus, 2 + 3k + 8 = 0, so 3k = -10, k = -10/3.