1⼀2+3⼀4+7⼀8+....+1023⼀1024

最好每一步都有解释(详细一点)
2024-12-02 23:15:53
推荐回答(2个)
回答1:

1/2+3/4+7/8+....+1023/1024
观察式子,分母为:2^n
分子为:2^n-1
所以:通项为:(2^n-1)/2^n=1-1/2^n
所以原式=1-1/2+1-1/2^2+1-1/2^3+....+1-1/2^10
=10-(1/2+1/4+1/8+...+1/2^10)
=10-1/2(1-1/2^10)/(1-1/2)
=10-1+1/2^10
=9+1/2^10
=9217/1024

回答2:


1024=2^10,所以有十个式子,所以
原式= 10-(1/2+1/4+1/8+....+1/1024)
=10-(1/2+1/4............+1/1024+1/1024-1/1024)
= 10-(1/2+1/4.......+1/512+1/512-1/1024)
=10-(1-1/1024)
=9+1/1024