If ana_nan is a geometric sequence and a1=5,r=1/2a_1=5, r=1/2a1=5,r=1/2, find ∑n=110an\sum_{n=1}^{10} a_n∑n=110an.
10(1−(1/2)10)10(1 - (1/2)^{10})10(1−(1/2)10)
5(1−(1/2)10)5(1 - (1/2)^{10})5(1−(1/2)10)
10(1−(1/2)9)10(1 - (1/2)^9)10(1−(1/2)9)
5(1−(1/2)11)5(1 - (1/2)^{11})5(1−(1/2)11)