Question

Given u = 3i − 8j and v = −4i + 8j, what is u • v? 73 8 −76 −56

Answer 1

Answer: -76 (choice C)

Step-by-step explanation:

We're applying the dot product.

u dot v = 3*(-4) + (-8)*8

u dot v = -12 - 64

u dot v = -76

The idea is that we multiply the x coordinates together, and the y coordinates together separately. Afterward you add the products. The result of any dot product is a scalar value, aka a single number.

The dot product is useful in many applications. One of which is to determine if two vectors are orthogonal.