Posted by Anonymous on Saturday, March 29, 2008 at 4:29pm.
If a = 3i + 2j  k and b = 2i + j calculate each magnitude.
a) a + b
I got sqrt3, but the answer at the back of the book says sqrt11.
2) If D(3,4,5) and E(2,1,5) are points in space calculate each expression and state what it represents.
OD
can you please do those and explain steps.

Math  Damon, Saturday, March 29, 2008 at 4:33pm
a + b = (32) i +(2+1) j +(1+0) k
= 1 i + 3 j 1 k
sqrt (1^1 + 3^2 + (1)^2 )
sqrt ( 1 + 9 + 1)
sqrt (11)
The book wins again :) 
Math  Anonymous, Saturday, March 29, 2008 at 4:39pm
Wow I accidentally put a  in front of 2 and ended up with 1. Thanks!

Math  Damon, Saturday, March 29, 2008 at 4:37pm
2) If D(3,4,5) and E(2,1,5) are points in space calculate each expression and state what it represents.
OD

I assume 0 is the origin (0,0,0)
so OD = (30)i + (40) j + (50) k
and
OD = sqrt (3^2 + 4^2 + 5^2)
=sqrt (9 + 16 + 25)
= sqrt(50)
= 5 sqrt(2)