INSTRUCTOR: Find u dot v where u is the vector 2 comma 9 comma negative 1, and v is the vector negative 3 comma 1 comma negative 4. Now, as the definition of the dot proctor goes, u dot v is going to be equal to the sum of the product of our components in a certain way. So we'll multiply the first component of each plus multiply the second components plus multiple the third and so on, if we have more dimensions.

So in this question, this means this will be 2 multiplied by negative 3 plus 9 multiplied by 1 minus 1 multiplied by negative 4. And this will result in a scalar, which is good. So that'll be negative 6 plus 9 plus 4. It should be 7. So u dot v is equal to 7.