Question

1、给出下列算式：3² -1² =1×8；5² - 3² =18 =2×8；7&

Answer 1

1.

(1) (2n+1)^2-(2n-1)^2=8n

(2)2011² -2009²=1005*8

2.

(1)(1/2+1/4+1/8+1/16+1/32+1/64+1/128+1/128)-1/128=127/128

(2)s= 1/2+1/2^2+1/2^3+1/2^4+…+1/2^n

2s=1+1/2+1/2^2+1/2^3+1/2^(n-1)

-得

s=1-1/2^n