If one root of the polynomial f (x) = 5x^{2} + 13x + k is reciprocal of the other, then the value of k is

Given;

f(x) = 5x^{2} + 13x + k

Let suppose roots are R and 1/R

Product of the roots = C/R = R×1/R

R×1/R = k/5

1 = k/5

So,

Here k = 5