.
a = 2 + square root of 3.
Find a^2 +1/a^2.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
First let us prove this statement:
If a =
, then
=
Indeed,
=
= 4 - 3 = 1, so the statement is proved.
Next,
+
=
. (*)
Notice that
=
+
= 4.
Therefore, we can continue (*) in this way:
+
=
=
= 16 - 2 = 14.
Answer. If a =
then
= 14.