Question

求等比数列的求和的例题.裂项求和法的

Answer 1

例如：等比数列1/2,1/4,1/8,...1/2^n

Sn=1/2+1/4+1/8+...+1/2^n

=(1-1/2)+(1/2-1/4)+(1/4-1/8)+...+(1/2^(n-1)-1/2^n)

=1-1/2^n