If a² - 4a - 1 = 0 then value of $${a^2} + \frac{1}{{{a^2}}} + 3a - \frac{3}{a}$$    is?

Solution (By Examveda Team)

$$\eqalign{ & {a^2} - 4a - 1 = 0 \cr & {a^2} - 1 = 4a \cr & a - \frac{1}{a} = 4 \cr & {\text{Squring both sides}} \cr & {a^2} + \frac{1}{{{a^2}}} - 2 = 16 \cr & \Rightarrow {a^2} + \frac{1}{{{a^2}}} = 18 \cr & \therefore {a^2} + \frac{1}{{{a^2}}} + 3a - \frac{3}{a} \cr & = {a^2} + \frac{1}{{{a^2}}} + 3\left( {a - \frac{1}{a}} \right) \cr & = 18 + 3 \times 4 \cr & = 18 + 12 \cr & = 30 \cr} $$