Question

Let u = <-5, -9>, v = <6, 8>. Find -8u - 2v.

<52, 88>
<-8, 2>
<112, -28>
<28, 56>

Answer 1

did you try doing what I suggested.

Answer 2

-8<-5,-9>=?
-2<6,8>=?

Answer 3

just apply the rules I showed

Answer 4

okay, thanks

Answer 5

a is a constant
so au=<-5a,-9a>
so if a=2
then 2u=<-10,-18>

Answer 6

I got <112, -28>

Answer 7

\[-8<-5,-9>=<40,72> \\ -2<6,8>=<-12,-16>\]
so you added 40 and -12 and then you added 72 and -16
and got 112 and -28 respectively ?

Answer 8

Oh, no. I added the 40 and 72, and the -12 and -16.... So I needed to add the 40 and -12 which is 28, and the 72 and -16 which is 56.

Answer 9

that sounds much better

Answer 10

<a,b>+<c,d>=<a+c,b+d> is the rule for adding vectors

Answer 11

Okay, that's where I was confused.

Answer 12

Thank you!