Which series is a geometric series with ∣r∣>1|r| > 1∣r∣>1?
∑n=1∞(0.9)n\sum_{n=1}^{\infty} (0.9)^n∑n=1∞(0.9)n
∑n=1∞(1.1)n\sum_{n=1}^{\infty} (1.1)^n∑n=1∞(1.1)n
∑n=1∞(12)n\sum_{n=1}^{\infty} (\frac{1}{2})^n∑n=1∞(21)n
∑n=1∞(−0.5)n\sum_{n=1}^{\infty} (-0.5)^n∑n=1∞(−0.5)n