Suppose that $ \sum_{n = 0}^{\infty} c_nx^n $ converges when $ x = - 4 $ and diverges when $ x = 6. $ What can be said about the convergence or divergence of the following series?
(a) $ \sum_{n = 0}^{\infty} c_n $
(b) $ \sum_{n = 0}^{\infty} c_n8^n $
(c) $ \sum_{n = 0}^{\infty} c_n( - 3)^n $
(d) $ \sum_{n = 0}^{\infty} ( - 1)^n c_n 9^n $