Question

if x=2+under root 3 find the value of x cube +1/x cube

Answer 1

x = 2 + root 3
 

1/x = 1/2 + root3 * 2-root3/2-root3
      = 2-root3/(2+root3)(2-root3)
      =  2-root3/4 - 3
       = 2-root3/1
      = 2-root3


therefore
  
 xcube + 1/xcube