Question

vector v= 3i-4j and w= 5i+3j, find 3v-2w. So far I got up to this step: click attached http://bamboodock.wacom.com/doodler/57f64b99-b187-47dc-97e0-68f452b0bf21
I dont what to do next.

Answer 1

the book said the next step is (9-10)i + (-12-6)j but i dont know why it became an addition

Answer 2

combine like terms

Answer 3

You are almost there already, you can basically use similar operations as addition and subtractions, in your case you want to add and subtract the components of each unit \( i, j \)

Answer 4

they are writing \(+\) because the final form looks like \(ai+bj\) but no one says \(a\) or \(b\) have to be positive

Answer 5

also...check your multiplication of 3 x 3!

Answer 6

i combined like terms so would it become (9 + 10)i - (-12+6) ???

Answer 7

oh i meant (-12+9)

Answer 8

i think the \(i\) and \(j\) are confusing you
suppose you had to simplify and combine like terms here
\[3(3x-4y)-2(5x+3y)\]what would you do?

Answer 9

9x-12y - 10x-6y

Answer 10

that is step one
step two is to combine like terms

Answer 11

so it would bit 9x-10x-12y-6y

Answer 12

what is \(9-10\)?

Answer 13

-x-18y!! oh i got it!!

Answer 14

yay! (whew)