So given two $r.v.$ $X_1, X_2$ who are $i.i.d.$ with probability dist. function:
$$p(k) = (1-r)r^k$$
with $k = 0,1,2,...$ and $0<r<1$
we want the Distribution of the $\min(X_1,X_2)$
So here is what I got:
$$P\bigg[\min(X_1,X_2)=k\bigg] = P\bigg[\min(X_1,X_2)\geq k\bigg] -P\bigg [\min(X_1,X_2)\geq k+1 \bigg] $$
$$P\bigg[\min(X_1,X_2)=k\bigg] =r^{2k} - r^{2k+2} = r^{2k}(1-r^2).$$
Is this correct?