(1+2^1/32)(1+2^1/16)(1+2^1/8)(1+2^1/4)(1+2^1/2)
上下同乘以(1-2^1/32),反复用平方差
=(1-2^1/32)(1+2^1/32)(1+2^1/16)(1+2^1/8)(1+2^1/4)(1+2^1/2)/(1-2^1/32)
=[1^2-(2^1/32)^2](1+2^1/32)(1+2^1/16)(1+2^1/8)(1+2^1/4)(1+2^1/2)/(1-2^1/32)
=(1-2^1/16)(1+2^1/16)(1+2^1/8)(1+2^1/4)(1+2^1/2)/(1-2^1/32)
=(1-2^1/8)(1+2^1/8)(1+2^1/4)(1+2^1/2)/(1-2^1/32)
=(1-2^1/4)(1+2^1/4)(1+2^1/2)/(1-2^1/32)
=(1-2^1/2)(1+2^1/2)/(1-2^1/32)
=(1-2)/(1-2^1/32)
=-1/(1-2^1/32)
=1/(2^1/32-1)