Evaluate the expression. r = , v = , w = v ⋅ w I keep doing it and I end up with (7,4,-8), which isn't one of my answer choices, what am I doing wrong?

Question

Evaluate the expression. r = <9, -7, -1>, v = <2, 2, -2>, w = <-5, -2, 6> v ⋅ w I keep doing it and I end up with (7,4,-8), which isn't one of my answer choices, what am I doing wrong?

geerky42 · Answer

dot product should be number, not vector.

geerky42 · Answer

Saying we have $\large a = \langle a_x,a_y,a_z\rangle$ and $\large b = \langle b_x, b_y, b_z \rangle$

Then we have $\large a\cdot b = a_xb_x+a_yb_y+a_zb_z$

anonymous · Answer

Oh okay so I'm doing v x w?

anonymous · Answer

I just did it and ended up with -26

geerky42 · Answer

$v\cdot w = -10+-4+-12 = \boxed{-26}$

So yeah.