Let u=3i−j, v=2i+j, w=i+2j Find the specified scalar. u•(v+w)

Answer 1

Let's start with the parenthesis.

v + w is the easier operation

v + w = 2i + j + i + 2j

= 3i + 3j by simply adding.

Next is a dot product.

(3i - j) • (3i + 3j)

To do the dot product simply multiply the coefficients of the i then add it to the product of j

= (3 * 2) + (-1 * 3)

= 6 - 3 = 3