If f(x)=∑n=0∞cnxnf(x) = \sum_{n=0}^{\infty} c_n x^nf(x)=∑n=0∞cnxn converges at x=3x=3x=3, which of the following is necessarily true?
R≥3R \geq 3R≥3
R<3R < 3R<3
R=3R = 3R=3
The series converges for x=4x=4x=4.