Answer:
You should write the vectors in their proper sequence: i , j, k
If the vectors are perpendicular their dot product must be zero:
1) A dot B is obviously zero since A and B have no common terms in i , j , k
2) looks like A = 2 i - 4 j + 3 k and B = i + 2 j + 2 k
A dot B = (2 * 1) + (-4 * 2) + (3 * 2) = 0
Note that the dot product produces a scalar with no direction (vector components)
Only i dot i, j dot j, and k dot k have components i dot j = zero, etc.
