C。解析:等差数列前 n 项和公式为 Sn = n(a1 + an) / 2 ,因为是前 5 项,所以 n = 5 ,a1 = 3 ,Sn = 45 ,可求出 a5 = 15 。通项公式 an = a1 + (n - 1)d ,即 15 = 3 + (5 - 1)d ,解得 d = 3 。选项 A 计算错误,应为 4 而非 2 ;选项 B 计算错误,应为 4 而非...
The sum of the first five terms of an arithmetic sequence is 50. If the first term is 5, what is the common difference? A. 3 B. 4 C. 5 D. 6 相关知识点: 试题来源: 解析 B。解析:设公差为 d,根据等差数列求和公式,S5=5a1+(5×4/2)d=50,a1=5 代入可得 25+10d=50,解得 d=25...
The sum of the first five terms in an arithmetic sequence (等差数列) is 30. The sum of the last five terms is 95. The sum of all the terms is 225. How many terms are there in this sequence? 相关知识点: 试题来源: 解析 18 一个等差数列的前五项和为30,最后五项和为95,所有项之和为...
A. \(na_1\) B. \(\frac{n}{2}(a_1 + a_n)\) C. \(n(a_1 + a_n)\) D. \(\frac{n}{2}a_1\) 相关知识点: 试题来源: 解析 B。中文解析:文章中给出等差数列前\(n\)项和公式为\(S_n=\frac{n}{2}(a_1 + a_n)\)。反馈 收藏 ...
是一道英语的数学题 请求哥哥姐姐们帮助!感激不尽!The points on this graph represent the first five terms of an arithmetic sequence.The height of each point is its distance from the x-axis,or the value of the y-coordinate of the po
Question: Write the first five terms of the arithmetic sequence with the first term, a1=5, and common difference, d=-2.The first term is ◻ (Type an integer or a simplified fraction.)The second term is ◻ (Type an integer or a simp...
If the first term of an arithmetic sequence is 5 and the common difference is 3, then the third term is ___. A. 11 B. 10 C. 12 D. 9 相关知识点: 试题来源: 解析 A。中文解析:首项\(a_1 = 5\),公差\(d = 3\),根据通项公式\(a_n = a_1 + (n - 1)d\),第三项\(a_...
百度试题 结果1 题目The first four terms of an arithmetic sequence are , , , and . What is the th term of this sequence?( ) A: B: C: D: E: 相关知识点: 试题来源: 解析 A N/A. 反馈 收藏
百度试题 结果1 题目【题目】T he first four terms of an arithmetic sequence arep, 9, 3p-q, and 3p+q. What is the 2010th term of this sequence?()A.8041B.8043C.8045D.8047E.8049 相关知识点: 试题来源: 解析 【解析】A 反馈 收藏 ...
Write down, in terms of n, an expressionfor the nth term of the sequence. 相关知识点: 试题来源: 解析 n+4 核心短语/句式:write down :写下来。in terms of :依照,根据句子译文:写出该数列的第n 项。 这是一个公差为4的等差数列。其第n 项为:n+4.反馈...