Question

How to find a vector when given its ratio with another vector?

Can someone please explain to me how to do question 1b? Thanks!

Answer 1

`vec(OR)=2ula-ulb`

Explanation:

`vec(AB)=3vec(AR)+2vec(RB)`

`rArrulb-ula=3(ulr-ula)+2(ulb-ulr)`

`rArrulb-ula=3ulr-3ula+2ulb-2ulr`

`rArrulr=ulb-ula+3ula-2ulb`

`rArrvec(OR)=ulr=2ula-ulb`