Posted by Cameron on .
Vectors "v" and "w" are given by v = 5i  2j and w = i + 3j. Find scalars r and s such that r ( v  w) = ( r + s )i  20j.

Vectors 
Anonymous,
r(vw)=(r+s)i20j
start with the i componnets.
r(vw) dot i=r+s
(5ri2rjri3rj)dot i= r+s
5rr=r+s
4r=s
Now the j components
r(vw)dot j=20
2r3r=20
r=4 then s=1
check my work, please 
Vectors 
Cameron,
WAT DO U MEAN BY DOT?

Correction  Vectors 
Reiny,
The answer given above is incorrrect
let v = [5,2) and w = [1,3]
then vw = [4,5]
so we want r[4,5] = [r+s, 20]
then 4r = r+s and 5r = 20
3r = s and r = 4
then r = 4, then s = 12
verification:
LS = r(vw)
= 4[4,5] = [16, 20]
RS = [r+s, 20 = 16, 20 ] = LS
My answer is correct!