there exists a postive integer N such that N > log(E)/ log(1-r), we have , 0 0 < 1-r <1, => log(1-r) <0 => Nlog(1-r) < logE, => log(1-r)^N (1-r)^N Solution there exists a postive integer N such that N > log(E)/ log(1-r), we have , 0 0 < 1-r <1, => log(1-r) <0 => Nlog(1-r) < logE, => log(1-r)^N (1-r)^N.