2.2: Finding constants and a unit vector

0606/21/M/J/20 — Question 5 · 5 marks

The vectors a\mathbf{a} and b\mathbf{b} are such that a=αi+j\mathbf{a} = \alpha\mathbf{i} + \mathbf{j} and b=12i+βj\mathbf{b} = 12\mathbf{i} + \beta\mathbf{j}.
(a)
Find the value of each of the constants α\alpha and β\beta such that 4ab=(α+3)i2j4\mathbf{a} - \mathbf{b} = (\alpha + 3)\mathbf{i} - 2\mathbf{j}.
[3]
(b)
Hence find the unit vector in the direction of b4a\mathbf{b} - 4\mathbf{a}.
[2]