If, r/13+13/r = 1 then the value of r3 is:

If, $\frac{r}{13}+\frac{13}{r} = 1$

Then the value of r³ is?

If we have x + \(\frac{1}{x}\) = 1

Then x³ = -1 always 

(\(\frac{r}{13}\))³ = -1

r³ = -2197