Question

If a and b be vectors in the space given by a = (i – 2j)/√5 and (2i + j + 3k)/√14, then the value of (2a + b).{(a × b) × (a – 2b)} is

Answer 1

Given |a| = 1 = |b| and a.b = 0

= 4 + 1 + 0

= 5