9514 1404 393
Answer:
970
Explanation:
It turns out that the radical terms cancel, so the result is an integer. You can find the integer value using your calculator. It is ...
(5 +2√6)³ +1/(5 +2√6)³ = 970
_____
The cube of 'a' is ...
(5+2√6)³ = 5³ +3·5²·2√6 +3·5·(2√6)² +(2√6)³
= 125 +3·50√6 +3·120 +48√6
a³ = 485 +198√6
The reciprocal of this is ...
b³ = 1/a³ = 1/(485 +198√6) = (485 -198√6)/(485² -6·198²) = (485 -198√6)/1
b³ = 485 -198√6
Then the sum is ...
a³ +b³ = (485 +198√6) +(485 -198√6) = 970