Formula 1: The sum of the first n terms of an arithmetic sequence where nth term is not known is given by:Sn = n/2 [2a + (n - 1) d]WhereSn = the sum of the initial n terms of arithmetic sequence, a = the first term, d = the common difference between the terms, n = the...
(b) gives 10a+50d=170(a)is 10a+45d=162Subtract 5d=8 so d=1.6 o.e.Solving for a a=17-5d so a=9(a) M1 for use of S, with n =10(b) 1st M1 for an attempt to eliminate a or d fro m their two linear equations2nd M1 for using their value of a or d to find the ...
百度试题 结果1 题目Find the sum of the arithmetic sequence.∑_(i=1)^∑(2i-3) 相关知识点: 试题来源: 解析 =3601a_1=2(1)-3=-1 a_(20)=2(20)-3=37 20 反馈 收藏
Learn what an arithmetic sequence is and explore different examples of an arithmetic sequence. Understand how to find the sum of an arithmetic...
The sum of the first n terms of an arithmetic sequence is given by Sn = 2n^2 + 3n. What is the common difference? A. 2 B. 3 C. 4 D. 5 相关知识点: 试题来源: 解析 C。首先,根据等差数列前 n 项和公式 Sn = n(a1 + an) / 2 = na1 + n(n - 1)d / 2,对比给定的 Sn ...
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 certain arithmetic sequence has 10 terms. The sum of the first and last term is 50. What is the sum of all the terms? A. 250 B. 275 C. 300 D. 325 相关知识点: 试题来源: 解析 B。解析:根据等差数列性质,若有 n 项,则 Sn = n(a1+an)/2。已知 n = 10,a1+an = 50,所以 ...
The sum of the first n terms of an arithmetic sequence is given by Sn = 2n^2 + 3n. What is the common difference? A. 4 B. 2 C. 6 D. 8 相关知识点: 试题来源: 解析 A。由 Sn = 2n^2 + 3n ,可得 a1 = S1 = 5 ,a2 = S2 - S1 = 12 - 5 = 7 ,所以公差 d = a2 - ...
Find the common difference and the first term in this sequence. 3【题目】In an arithmetic sequence, the sum of the first 10 terms is 100, and the sum of the first 20 terms is 250.Find the sum of the first 100 terms in this sequence....
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...