Question

Pre-calc help
Medal + Fan

Evaluate the expression:

v ⋅ w

Given the vectors:

r = <5, -5, -2>; v = <2, -8, -8>; w = <-2, 6, -5>

Answer 1

I know it's dot product but I always get these wrong for some reason. @zepdrix

Answer 2

@sweetburger

Answer 3

stack the vectors, and multiply down the columns, then add the results

Answer 4

That's what I do but it ends up being wrong. I'll try again

Answer 5

v = < 2, -8, -8>
w = <-2, 6, -5>
---------------
v.w= ____________

Answer 6

if we try to work formula, theres a higher risk of error since we are trying to do placements ... this way the information is already organized in a succinct manner.

Answer 7

-4 -48 +40= -12

Answer 8

yep

Answer 9

Thanks

Answer 10

I really like cross product that way as well :)
Instead of setting up the i j k with the numbers and all that fancy stuff, just stack the vectors.

Answer 11

:) and shortcut the 3x3 det.

Answer 12

well, im used to ijk inserts, so i guess im old fashioned lol

Answer 13

-(16z-48x-10y)
x y z x y
< 2, -8, -8 2 -8
<-2, 6, -5 -2 6
+(40x+16y+12z)

( 40x +16y +12z)
-(-48x -10y +16z)
----------------
88x, 26y, -4z

Answer 14

Oh the Rule of Sauris thing or whatever?
Where you extend the first two columns? Yaaaa that's handy :3

Answer 15

my linearA teacher was 'by the book' but was impressed i always got the right answers