Please solve it

Given a = 2 + ?3?? (1/a) = 1 / (2 + ?3)Multiply and divide by (2 ? ?3)?? (1/a) = (2 ? ?3) / [(2 + ?3)(2 ? ?3)]?? (1/a) = (2 ? ?3) / [4 ? 3]?? (1/a) = (2 ? ?3)?? a + (1/a) = (2 + ?3) + (2 ? ?3)?= 4