What is the unit vector of v: <-6, -8>?

Answer 1

sqrt(36 + 64) = sqrt 100 = 10
so that vector is ten units long.
If you divide each component by 10, you will get a vector of length one in that same direction so
< -6/10 , -8/10 >

or
< -3/5 , -4/5 >

by the way this is a 3,4,5 right triangle :)