Find the unique triple (x,y,z) of positive integers such that x<y<z and
\frac{1}{x} - \frac{1}{xy} - \frac{1}{xyz} = \frac{1}{3}
1x−1xy−1xyz=13
Multiply by x on both sides
1−1y−1yz=x3
x < 3
if x = 2:
1y+1yz=13
1+1z=y3
Meaning z = 3, which cannot work in x > y > z
if x = 1:
1y+1yz=23
1+1z=2y3
Also meaning z = 3, which doesn't work
Therefore, there is no solution.