Question

Given u = 4i - 7j and v = -6i + 9j, what is u • v?

-87
-82
26
39

Answer 1

The dot product of u = 4i - 7j and v = -6i + 9j is:

u • v = (4i)(-6i) + (-7j)(9j) = -24i^2 - 63j^2

Since i^2 = j^2 = -1, we have:

u • v = -24(-1) - 63(-1) = 24 - 63 = -39

Therefore, the answer is —87