求1/2+1/2²+1/2³+1/2四次方.?
求1/2+1/2²+1/2³+1/2四次方...+1/2N次方的值
1/2+1/2²+1/2³+1/2四次方...+1/2N次方=a a-1/2=1/2²+1/2³+1/2四次方...+1/2N次方 (1/2)*(1/2+1/2²+1/2³+1/2四次方...+1/2N)= (1/2²+1/2³+1/2四次方...+1/2N次方)+1/2N+1次方= a-1/2+1/2N+1次方=a/2 a/2=1/2-1/2N+1次方 a=1-1/2N次方