Posted by Tabby on Sunday, April 22, 2012 at 7:32pm.
write MN as the sum of unit vectors for M(3/4, 5, 2/3) and N(6, 9, 3/5).
Someone help me please?

Sum Of Unit Vectors?  Reiny, Sunday, April 22, 2012 at 8:52pm
vector MN = [6+3/4 , 95 , 3/52/3]
= [ 27/4 ,  14 , 1/15]
magnitude of MN = √(729/16+ 196 + 1/225)
= √(870354/3600)
= appr. 15.549
so a unit vector in the direction of MN
= 1/15.549 [27/4, 14, 1/15]
= [ .434 , .900 , .004]
check: .434^2 + (.9)^2 + (.004)^2 = .99918 (very close to 1, that's good)
so [ .434 , .900 , .004]
= .434[1,0,0]  .9[0,1,0]  .004[0,0,1] 
Sum Of Unit Vectors?  Tabby, Sunday, April 22, 2012 at 9:20pm
Thank you so much for providing a clear explanation!! :)