(x@3) = x ( x +1)( x +2)
(x@3)@2 = x ( x+1)( x + 2 ) [ x ( x + 1 ) x+2) + 1] = 3660
∵[ x ( x + 1) ( x+ 2) + 1] 比 x ( x + 1) ( x + 2) 多1
3660 = 60 X 61
∴x ( x+1) x+ 2 ) = 60 = 3 X 4 X 5
∴x = 3
[x(x+1)(x+2)]·[x(x+1)(x+2)+1]=3660
[x(x+1)(x+2)]=60
x=3