Question

Pls answer this question

Answer 1

Answer:

ans is 6

hope this is helpful

Answer 2

Answer: 6

Step-by-step explanation:

It is given

               a = 9 + 4$\sqrt{5}$

∴$\frac{1}{a}$ =  $\frac{1}{ 9 + 4\sqrt{5} }$

    = $\frac{(9-4\sqrt{5})}{(9+4\sqrt{5})(9-4\sqrt{5})}$

    =  $\frac{9-4\sqrt{5} }{9^{2}-(4\sqrt{5})^2}$

    = $\frac{9-4\sqrt{5} }{81-80}$

    = 9 - 4$\sqrt{5}$

∴ $\frac{1}{3}(a+\frac{1}{a})$ = $\frac{1}{3}$$(9+4\sqrt{5}+9-4\sqrt{5})$

                = $\frac{1}{3}(18)$

                = 6 (answer)