Determine whether the vectors u and v are parallel, orthogonal, or neither. u = < 1, -2> , v = < -4, 8>

Two vectors are orthogonal(perpendicular) if their dot-product is 0

so.. let's check that (1*-4) + (-2*8) -> -4-16 -> -20

so, they're not orthogonal

two vectors are parallel if one is the scalar multiplication of the other, namely, they're just multiples of each other

hmm let's see  1, -2, now if we do say -4<1,-2> we end up with < (-4*1) , (-4*-2)>  which is < -4 , 8>

thus.. they're parallel then