If a= 3 +2 root 2 , then find the value of a^2 - 1/a^2 ????

Answer 1

a = 3+2√2
a^2 = 9 + 12√2 + 8 = 17+12√2
1/a^2 = (17-12√2)/(289-288) = 17-12√2

a^2 + 1/a^2 = 34

Answer 2

sorry I didn't see the minus sign. But it's easy to fix. What do you get?