If f(x)=∑n=0∞anxnf(x) = \sum_{n=0}^{\infty} a_n x^nf(x)=∑n=0∞anxn, which expressions equal f′(x)f'(x)f′(x)?
∑n=0∞n⋅anxn−1\sum_{n=0}^{\infty} n \cdot a_n x^{n-1}∑n=0∞n⋅anxn−1
∑n=1∞n⋅anxn−1\sum_{n=1}^{\infty} n \cdot a_n x^{n-1}∑n=1∞n⋅anxn−1
∑n=0∞(n+1)⋅an+1xn\sum_{n=0}^{\infty} (n+1) \cdot a_{n+1} x^n∑n=0∞(n+1)⋅an+1xn
Both (b) and (c)