need help please solve this

 (x+1/x)³= x³ + i/x³+3 (x) (1/x) (x+ 1/x)   (using identity (x+y)³ = x³ + y³ + 3xy(x+y) )

(3) ³ = x³ + 1/x³+3 ( 3)

27= x³ + 1/x³ + 9

x³ +1/x³ = 27-9=18

Regards