Question

If a = 6 - square root 35.Then find a^2 + 1/a^2

Answer 1

a=6-rt35, 1/a = 1/(6-rt35)= 6+rt35/36-35= 6 + rt35
a+ 1/a=12
(a+1/a)^2 = a^2 + 1/a^2 + 2
144= a^2 + 1/a^2 +2
a^2 + 1/a^2= 142