题目
Problem
An arithmetic progression has first term and common difference 2. The th term is 55 and the sum of the first terms is 5760. Find the values of and .
[6]
题目中文翻译
一个等差数列的首项为 ，公差为 2。第 项为 55，前 项的和为 5760。求 和 的值。
[6]
An arithmetic progression has first term and common difference 2. The th term is 55 and the sum of the first terms is 5760. Find the values of and .
一个等差数列的首项为 ，公差为 2。第 项为 55，前 项的和为 5760。求 和 的值。