Find the value of h so that set {a1,a2,a3} does not span R3

Question

a1 = [16 -16 -4], a2 = [h -13 -2], and a3 = [-21 15 3]

Answer 1

If this vectors linearly dependent then they not span R₃.

So, det([16 -16 -4], [h -13 -2], [-21 15 3]) = 0; h = 23