Please help with the following questions:

6. If the power series ) a,(x - 4)" converges at a = 7 and diverges at a = 9, which of the following must be true? I. The series converges at r = 1. Il. The series converges at a = 2. Ill. The series diverges at = = - 1. A I only II only C I and Il only D ll and ill only 7. The radius of convergence for the power series - is equal to 1. What is the interval of convergence? n -45x