Math Help - Finding a Vector

1. Finding a Vector

Find a vector of length 3 which has:
a) the same direction as 5i + 2j
b) the opposite direction to 4i + 5j

$a) |5-2j| = (5^2 + (-2)^2)^.5 = (29)^.5$
then
$3[(1/(29)^.5)(5i + 2j)] = 15/(29)^.5i - 6/(29)^.5j$
the $^.5$ is square root...but I don't know how to show that on here. is my math correct?

and is b) done the same way except I would multiply the whole thing by -1?

Thanks

2. $\left\| {5i - 2j} \right\| = \sqrt {29}$ to need to learn this.
So the vector you want is $\frac{{15}}{{\sqrt {29} }}i - \frac{6}{{\sqrt {29} }}j$

3. Originally Posted by Plato
$\left\| {5i - 2j} \right\| = \sqrt {29}$ to need to learn this.
So the vector you want is $\frac{{15}}{{\sqrt {29} }}i - \frac{6}{{\sqrt {29} }}j$
ah, okay, so my math was correct.
I'll go ahead and assume the same format is used for b), but it's negative.

Thanks