Consider the following premises. ~q_9. r_3 -> q_9. u -> r_3. r_3 or ~q_9. Can we infer ~u from them?
 From r_3 or ~q_9 we can infer q_9 -> r_3. From r_3 -> q_9, q_9 -> r_3 we can infer r_3 <-> q_9. From r_3 <-> q_9, ~q_9 we can infer ~r_3. Finally, from u -> r_3, ~r_3 we can infer ~u. Therefore, the answer is yes.