是不是1-1/2-1/4-1/8-1/16-1/32-1/64-1/128=?
应用等比数列求和公式:Sn=a1(1-q^n)/(1-q) =(a1-an×q)/(1-q) (q≠1)
上式=1-(1/2+1/4+1/8+1/16+1/32+1/64+1/128)
=1-(1/2*(1-1/2^7)/(1-1/2))=1/128
是不是1-1/2-1/4-1/8-1/16-1/32-1/64-1/128=?
应用等比数列求和公式:Sn=a1(1-q^n)/(1-q) =(a1-an×q)/(1-q) (q≠1)
上式=1-(1/2+1/4+1/8+1/16+1/32+1/64+1/128)
=1-(1/2*(1-1/2^7)/(1-1/2))=1/128