Question

help with this vector problem? (attachment)

Answer 1

-4u = <-4(3) , -4(5) > = -4u = <-12, -20)
2v = <2(4) , 2(-4) > = 2v = <8 , -8>

So to evaluate -4u - 2v

we do
< -12 - 8, -20 - (-8) > ?

can you evaluate this?

Answer 2

yeah i can, thanks again!

Answer 3

i got <-20, -12> and then used that for -4u-2v and got 104 but thats not an answer choice

Answer 4

i couldnt figure out of that was a dot or minus sign between the two

Answer 5

let me see the pick closely...

Answer 6

It its a dot product. just do this

-4u . -2v

-2v = <-2(4) , -2(-4) > = -2v = <-8, 8>

Than we know -4u = <-12 , -20)

So it would ne

= < (-12)(-8) + (-20)(8) > =

try to evaluate this.

Answer 7

ok i got -64 which is an answer choice. thanks

Answer 8

cool yw =))