DAU COROANĂ, calculati

9 / √ 18 - 9 / √8 + 9 / 6√2 - 9 / 6√8 =
= 9 ( 1 / 3√2 - 1 / 2√2 + 1 / 6√2 - 1 / 12√2) =
= 9 ( √2 / 6 - √2 / 4 + √2 / 12 - √2 / 24 ) =
= 9 ( 4√2 - 6√2 + 2√2 - √2 ) / 24 =
= 9× ( - √2 ) / 24 =
= - 3√2 / 8