1.求1/2+1/2^2+1/2^3+…+1/2^10的值?2.求1/2+1/2^2+1/2^3+…+1/2^n的值?
问题描述:
1.求1/2+1/2^2+1/2^3+…+1/2^10的值?2.求1/2+1/2^2+1/2^3+…+1/2^n的值?
答
利用等比数列的求和公式:
1/2+1/2^2+1/2^3+…+1/2^10
=1/2(1-(1/2)^10)/(1-1/2)
=1-(1/2)^10
=1023/1024
1/2+1/2^2+1/2^3+…+1/2^n
=1/2(1-(1/2)^n)/(1-1/2)
=1-(1/2)^n