Question

Given that v = (5,-4,4) and w = (9,-2,7) evaluate v • w.

A. 81
B. 19
C. (45,8,28)
D. (-40,-16,-8)

Answer 1

81

Explanation:

Evaluating v • w

Recall: Given vectors a and B in Cartesian plane, x, y and z

vector a = [ax ay az] and b = [bx by bz]

The dot product is :

a•b = axbx + ayby + azbz

Using the relation above,

v • w = (5*9) + (-4*-2) + (4*7)

v • w = 45 + 8 + 28

v • w = 81

Hence, v • w = 81