Answer: -8.
- A 0
- B -8
- C 8
- D -6
Correct answer: B. -8
Explanation: a.b = (2)(1) + (3)(-2) + (-1)(4) = 2 - 6 - 4 = -8.
Triangle law of vector addition: placing vector b at the head of vector a, the diagonal from the start to the final head gives the resultant a + b.
Concept context
Vectors, dot product, cross product, and geometric applications