If one zero of the polynomial 3x^2 + 12x - k is reciprocal of the other , then find the value of k.

By Vieta's formula, \(\text{product of roots} = \dfrac{-k}3\).

But since one zero is the reciprocal of the other, product of roots is 1.

Therefore, \(\dfrac{-k}3 = 1\). That means k = -3.