Find a.b if a = 4i + 8j, b = -2i + 3j

Solution:

Given, a = 4i + 8j, b = -2i + 3j

We have to find a.b

If the two vectors are expressed in terms of unit vectors, i, j, k, along the x, y, z axes, then the scalar product is given by

a.b = a₁b₁ + a₂b₂ + a₃b₃

Here, a₁ = 4, a₂ = -2, b₁ = 8 and b₂ = 3

a.b = (4i + 8j).(-2i + 3j)

= 4(-2) + 8(3)

= -8 + 24

= 16

Therefore, a.b = 16

Find a.b if a = 4i + 8j, b = -2i + 3j

Summary:

If a = 4i + 8j, b = -2i + 3j, then a.b is 16.