2. Let u = 2i − 5j and v = 10i − 25j. Find (a) u+v (b) u+1v 5 (c) u·v (d) a unit vector in the direction of u (e) Are u and v orthogonal?

Guest Dec 3, 2015

#4**+15 **

a. u + v = < 2i + 10i, -5j - 25j > = < 12i - 30j >

b. This doesn't make any sense to me......

c. u (dot) v = ([2)(10) + (-5)(-25)] = 20 + 125 = 175

d. The unit vector is given by : < 2 / sqrt [ 2^2 + (-5)^2]i , -5 / [ 2^2 + (-5)^2] j > =

< 2/sqrt(29) i , -5/sqrt(29) j >

e. For the vectors to be orthogonal, the dot product would have to = 0......it was shown in (c) that this is not the case

CPhill
Dec 3, 2015

#3**0 **

That is not helpful guest.

If you have time to write all that then you have time to do a quick internet search and send our guest to a net page that might be helpful.

OR you culd even just suggest this and give them a sensible word search suggestion like.

"How do I subtract vectors" There are bound to be some great you tubes on it :)

Melody
Dec 3, 2015

#4**+15 **

Best Answer

a. u + v = < 2i + 10i, -5j - 25j > = < 12i - 30j >

b. This doesn't make any sense to me......

c. u (dot) v = ([2)(10) + (-5)(-25)] = 20 + 125 = 175

d. The unit vector is given by : < 2 / sqrt [ 2^2 + (-5)^2]i , -5 / [ 2^2 + (-5)^2] j > =

< 2/sqrt(29) i , -5/sqrt(29) j >

e. For the vectors to be orthogonal, the dot product would have to = 0......it was shown in (c) that this is not the case

CPhill
Dec 3, 2015