(2.247) 3 + (1.730) 3 + (1.023) 3 -3 x 2.247 x 1.730 x 1.023 / [(2.247) 2 + (1.730) 2 + (1.023) 2 - 2.247 x 1.730 - 1.730 x 1.023 - 2.247 x 1.023] =?

We know that, a³ + b³ + c³ - 3abc
= (a + b + c) (a² + b² + c² - ab - bc - ca)
⇒ (a + b + c) = (a³ + b³ + c³ - 3abc/a² + b² + c² - ab - bc - ca) ....(i)
Given that,
(2.247)³ + (1.730)³ + (1.023)³ - 3 x 2.247 x 1.730 x 1.023/ (2.247)² + (1.730)² + (1.023)² - (2.247 x 1.730) - (1.730 x 1.023) - (2.247 x 1.023)
= 2.247 + 1.730 x 1.023) - (2.247 x 1.023)
= (2.247 + 1.730 + 1.023) [from Eq.(i)]
= 5.000 = 5