Question

Given the vectors v=3i-2j and w=-i+5j, find v · w.

Answer 1

v.w = -13

Explanation:

v.w = (3i - 2j).(-i + 5j) = 3 × -1 × i.i + 3 × 5 × i.j + -2×-1 × j.i + -2×5 × j.j

i.i = j.j = 1 , i.j = j.i = 0

→

v.w = -3 - 10 = -13

Answer 2

v * w = (3i - 2j) *(-i + 5j) = 3(-1) + (-2)(5) = -3 + -10 = -13

Hope that helps!