The corona theorem and Bass stable rank for $M(D(sum_{i=1}^k a_i delta_{zeta_i}))$

In this paper, we prove the corona theorem for $M(D(mu_k))$ in two different ways, where $mu_k = sum_{i=1}^k a_i delta_{zeta_i}$. Then we prove that the Bass stable rank of $M(D(mu_k))$ is one.