Vectors question. Help!?

Question

Vectors question. Help!?
Given that the vector ai + 3j is parallel to the vector 2i + 12j, find a

Answer 1

Parallel vectors are multiples of one another. So 2i+12j is a multiple of ai+3j.


Notice that 12j is 4*3j. So the second vector is 4 times the first vector.


So 4*a=2

---> a=2/4=1/2


This means a=1/2


Notice if we multiply 1/2 by 4 we'll get 2

Answer 2

ai + 3j = x (2i + 12j)

3 = 12x
x = 1/4

ai + 3j = (1/2) i + 3j

a = 1/2