If $\sum _ { n = 1 } ^ { \infty } c _ { n } x ^ { n }$ is convergent at $x = 3$ , what can be said about the convergence or divergence of the following series?
(a) $\sum _ { n = 1 } ^ { \infty } c _ { n } 4 ^ { n }$ (b) $\sum _ { n = 1 } ^ { \infty } c _ { n } ( - 2 ) ^ { n }$ (c) $\sum _ { n = 1 } ^ { \infty } c _ { n } ( - 3 ) ^ { n }$

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The Answer of If $\sum _ { n = 1 } ^ { \infty } c _ { n } x ^ { n }$ is convergent at $x = 3$ , what can be said about the convergence or divergence of the following series?
(a) $\sum _ { n = 1 } ^ { \infty } c _ { n } 4 ^ { n }$ (b) $\sum _ { n = 1 } ^ { \infty } c _ { n } ( - 2 ) ^ { n }$ (c) $\sum _ { n = 1 } ^ { \infty } c _ { n } ( - 3 ) ^ { n }$

If ∑n=1∞cnxn\sum _ { n = 1 } ^ { \infty } c _ { n } x ^ { n }∑n=1∞​cn​xn

If $\sum _ { n = 1 } ^ { \infty } c _ { n } x ^ { n }$