WebSn=An²+Bn+C,｛an｝成等差数列的充要条件为C=0；. S1=A+B+C=a1. S (n-1)=A (n-1)²+B (n-1)+C. an=Sn-S (n-1)=A (2n-1)+B. 已知a1和an可求等差数列前n项和为. Sn= (a1+an)n/2= … Web17 May 2024 · The first-term formula comes from substituting in n = 1, since n is the variable being used to denote which term we're looking at. a ∗ 1 2 + b ∗ 1 + c = a + b + c. The difference between the first two terms comes from writing down the first and second terms and taking their difference: ( a ∗ 2 2 + b ∗ 2 + c) − ( a ∗ 1 2 + b ∗ 1 + c) = a ∗ 3 + b
If the terms of a sequence are t1, t2, t3, ..., tn, what is the value
Web—n(an2 + bn + c) r=n+l where a, b and c are integers to be found. (4) 3. (a) Using the formula for r write down, in terms of n only, an expression for (b) Show that, for all integers n, … WebConsider the sequence defined by tn = an2 + bn + c. If t2 = 3, t4 = 13 and t7 = 113, show that 3tn = 17n2 – 87n + 115 from Mathematics Sequences and Series Class 11 CBSE … harvey jang cisco
等差数列{an}的前n项和sn=an^2+bn+c,则c=_百度知道
Web23 Mar 2013 · c=0，利用等差数列求和公式很容易得到。. ∴ Sn=na1+n (n-1)d/2= (d/2)n²+ (a1-d/2)n, ∴ 无常数项。. c=0，利用等差数列求和公式很容易得到。. 2015-02-08 已知数列 … WebSolution Verified by Toppr Given Sum of n terms is S n=3n 2−4n So Sum of n−1 terms is S n−1=3(n−1) 2−4(n−1) =3n 2−6n+3−4n+4 =3n 2−10n+7 Sum of n terms is equal to sum of n−1 terms plus n th term n th term =S n−S n−1=3n 2−4n−(3n 2−10n+7) n th term =6n−7 Was this answer helpful? 0 0 Similar questions The sum of first n terms of an AP is 3n 2−n. Web26 Feb 2024 · Adapun nilai suku ke-n (Un) adalah nilai suku pertama ditambah dengan beda dikalikan dengan n-1. Dilansir dari Math is Fun, rumus suku ke –n barisan aritmatika … harvey james watches