我想問問一條方程(不是恆等式)~要證明他左右相等~是否不能~ 因為有時是知道條方程如何計算~~~但不知如何證明~ 以下為原題目(出自:Mathematics Today 5A , page 56 第10題) The first term and the common ratio of a gemetric sequence are both 2. (a)Express each of the following in terms of n. (i)The sum of the first n terms. (ii)The sum of the first 2n terms. (b)If the sum of the first 2n terms of the geometric series is 65 times the sum of the first n terms,

(ii)hence find the value of n.

Last edited by cs55555 on Tue Sep 07, 2004 7:46 pm; edited 6 times in total